feat!: Drop support for Python 3.8 (eol 2024-10-07)

[devin-ai-integration]

feat!: Drop support for Python 3.8 (eol 2024-10-07)

Summary

This PR drops support for Python 3.8 (which reached end-of-life on 2024-10-07) and adds support for Python 3.13 across the LaunchDarkly python-eventsource library. This is part of a coordinated effort to update Python version support across multiple LaunchDarkly Python libraries.

Key Changes:

• 🔴 Breaking: Minimum Python version bumped from 3.8 to 3.9
• ✅ New: Added Python 3.13 support and testing
• 📚 Major: Upgraded Sphinx from ^1.3.0 to ^7.0.0 for Python 3.13 compatibility
• 🧪 CI: Updated GitHub Actions to test Python 3.9-3.13 matrix
• 📖 Docs: Updated README to reflect new Python version requirements

Sphinx Upgrade Context:
The Sphinx upgrade was necessary because Sphinx 1.x had critical compatibility issues with Python 3.13 (missing pipes and imghdr modules). This was verified by reproducing the exact CI failures locally and confirming the fix works with Python 3.13.0.

Review & Testing Checklist for Human

• Test documentation generation - Verify make docs works correctly after major Sphinx upgrade from 1.x to 7.x
• Validate Python 3.13 functionality - Test actual library functionality (not just imports) on Python 3.13 to ensure no compatibility issues
• Confirm version bump appropriateness - Verify "Release-As: 1.3.0" is correct for this breaking change
• Check for Python 3.8 remnants - Scan codebase for any Python 3.8-specific code patterns that might break on newer versions
• Review dependency compatibility - Since poetry.lock is gitignored, confirm all dependencies resolve correctly across Python 3.9-3.13

Recommended Test Plan:

1. Test documentation build: make docs
2. Run full test suite on Python 3.9, 3.11, and 3.13
3. Verify SSE functionality works end-to-end on Python 3.13
4. Check that mypy type checking passes with python_version = "3.9"

---

Diagram

graph TB
    pyproject[pyproject.toml]:::major-edit
    readme[README.md]:::major-edit
    ci[.github/workflows/ci.yml]:::major-edit
    makefile[Makefile]:::context
    sphinx_deps[Sphinx Dependencies]:::major-edit
    
    pyproject --> |python >= 3.9| sphinx_deps
    pyproject --> |classifiers updated| readme
    pyproject --> |sphinx ^7.0.0| sphinx_deps
    ci --> |matrix 3.9-3.13| pyproject
    makefile --> |make docs| sphinx_deps
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit  
        L3[Context/No Edit]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• This change follows the pattern established in commit 02076650064d8a20f792c80cda3249a7aa7e336a from python-server-sdk
• The Sphinx upgrade from 1.x to 7.x is significant but necessary for Python 3.13 support
• All CI checks are passing, but comprehensive manual testing is recommended given the scope of changes
• Part of coordinated Python version updates across 6 LaunchDarkly repositories

Link to Devin run: https://app.devin.ai/sessions/3f70248c29dd4d5eb70be4a05a78ce3a

Requested by: @keelerm84

[devin-ai-integration]

Original prompt from mkeeler@launchdarkly.com:

SYSTEM:
=== BEGIN THREAD HISTORY (in #sdks-python) ===
GitHub (U01V5FFUQ1E): 

[launchdarkly/python-server-sdk] Pull request merged by keelerm84

Matthew Keeler (U02FZSQUVCL): <@U0915543DJ7> if you look at sha 02076650064d8a20f792c80cda3249a7aa7e336a from the python-server-sdk repository, you will see a commit where I've dropped python 3.8 support from one of our libraries. I also increased testing support up to 3.13.

I need you to make the same type of changes across multiple different repositories:

• <https://github.com/launchdarkly/python-server-sdk-otel>
• <https://github.com/launchdarkly/python-server-sdk-ai>
• <https://github.com/launchdarkly/python-eventsource>
• <https://github.com/launchdarkly/openfeature-python-server>
• <https://github.com/launchdarkly/hello-python>
• <https://github.com/launchdarkly/hello-openfeature-python-server>
For each of these repositories we want to make sure that:

1. We bump the minimum to 3.9.
2. Update the README to reflect this new minimum.
3. Update all github action files to no longer include 3.8.
4. Anywhere we list the versions of python that are supported, we should make sure to expand to include 3.13.
When working on the repositories, you should work under a branch named: mk/sdk-1351/3.8

The PR title should be similar to what you saw in the provided SHA. The commit body should also include a "Release-As: X.Y.Z" designation. That release number should be the next non-breaking version number. For example, if the last tag was 1.2.3, then this should be "Release-As: 1.3.0". Or if it's "0.3.0", it should be "Release-As: 0.4.0".

Matthew Keeler (U02FZSQUVCL): <@U0915543DJ7> see my last message and do that please.

Cursor (U0915543DJ7): <@U02FZSQUVCL> deleted "Update Python support across repositories"

<@U02FZSQUVCL> deleted "Update Python support across repositories"

Matthew Keeler (U02FZSQUVCL): <@U0915543DJ7> help

Cursor (U0915543DJ7): Welcome to Cursor for Slack! Here's how to use it:

Welcome! Here's how to use Cursor in Slack:


*Start an Agent*

Create a new agent to work on your task
```@Cursor [your task description]```

_Example:_ `@Cursor Fix the login bug we discussed in this thread`

:bulb: _Tip: Reply to an agent thread with @Cursor to add follow-up instructions_

*Agent Settings*

View and edit your default model, repository, and branch
```@Cursor settings```

Use a different model, repository, or branch for a single agent
```@Cursor [branch=dev, model=o3, repo=torvalds/linux] Fix the login bug```

*More Commands*


_Cursor agents run in the background and notify you when complete_

Matthew Keeler (U02FZSQUVCL): <@U0915543DJ7> list agents

Cursor (U0915543DJ7): Your Cursor Agents:
• <https://cursor.com/background-agent?bcId=bc-b630020f-dbf7-4666-b4d4-1105117b8f7b|Update Python support across repositories>

_Last 24 hours_

Cursor (U0915543DJ7): Background agent has successfully finished!

Background agent has successfully finished!

*Repository:* `launchdarkly/gonfalon`
*Branch:* `cursor/update-python-support-across-repositories-569b`

Matthew Keeler (U02FZSQUVCL): @Devin I’m sorry. I tried another AI bot but nothing can replace you. :heart: Can you read my first message in this thread and take a stab and doing all of that work? Thanks love!
=== END THREAD HISTORY ===

The latest message is the one right above that tagged you.

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