Bump version to 2.4.3

[igerber]

Summary

• Bump version to 2.4.3 across all version files (__init__.py, pyproject.toml, rust/Cargo.toml)
• Add CHANGELOG.md entry for v2.4.3 covering the TripleDifference rewrite (PR Rewrite TripleDifference to match R's triplediff::ddd() #169) and review status update (PR Update TripleDifference summary table to reflect completed review #170)

Methodology references (required if estimator / math changes)

• N/A - version bump only, no methodology changes

Validation

• No test changes
• Version strings verified consistent across all 3 files

Security / privacy

• Confirm no secrets/PII in this PR: Yes

---

Generated with Claude Code

[github-actions]

Overall Assessment: ⚠️ Needs changes

• Changelog announces a substantive TripleDifference rewrite, methodology tests, benchmarks, and registry updates, but none of those code/test/doc artifacts are in this PR. This makes the release notes misleading and blocks methodology verification for what’s claimed.
• Version bumps are consistent across diff_diff/__init__.py, pyproject.toml, and rust/Cargo.toml.
• No estimator/math/SE code changes appear in this diff, so methodology adherence cannot be evaluated from code.
• No security issues detected in changed files.

Methodology

• P1 – Mismatched method claims vs. diff contents
  Impact: Release notes claim a TripleDifference rewrite and methodology changes that are not present in this PR, preventing any verification against docs/methodology/REGISTRY.md and cited papers. This is a process/methodology integrity issue for a causal inference library.
  Evidence: CHANGELOG.md:L3-L31
  Concrete fix: Either (a) move the 2.4.3 changelog entry to the PR that actually contains those estimator/test/registry changes, or (b) include the actual code changes, tests, and registry updates in this PR so the methodology review can be performed.

Code Quality

• No findings. Only version strings and changelog changed.

Performance

• No findings. No runtime code changes.

Maintainability

• No findings.

Tech Debt

• No findings.

Security

• No findings in modified files.

Documentation/Tests

• P1 – Changelog references tests/benchmarks/registry updates not in diff
  Impact: Documentation claims new tests and benchmark scripts that are not added here, which is misleading for users and reviewers.
  Evidence: CHANGELOG.md:L3-L31
  Concrete fix: Align the changelog entry with actual changes in this PR, or add the referenced tests/benchmarks/registry updates to this PR.

Notes

• I did not run tests (not requested).
• If this is intended as a pure version bump, consider moving the 2.4.3 changelog content into the PR that introduced those estimator changes, and keep this PR to version strings only.