fix: update black to fix ReDoS vulnerability (#582)

## Summary
- Addresses Dependabot alert #65 (medium severity)
- Updates `black` to ≥24.3.0 to fix CVE-2024-21503 (Regular Expression
Denial of Service)
- Added explicit constraint in dev dependencies

## Test plan
- [x] `uv lock` completes successfully
- [x] black version updated to 26.1.0
- [x] CI tests pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Vlada Dusek <v.dusek96@gmail.com>

Author: B4nan

pyproject.toml

@@ -42,6 +42,11 @@ dependencies = [
 
 [dependency-groups]
 dev = [
+    # TODO: Remove this constraint once pydoc-markdown updates its dependencies.
+    # Package pydoc-markdown is unmaintained and pins old docspec-python with vulnerable black.
+    # See https://github.com/apify/apify-client-python/pull/582/ for more details.
+    # We explicitly constrain black>=24.3.0 to override the transitive dependency.
+    "black>=24.3.0",
     "dycw-pytest-only<3.0.0",
     "griffe",
     "poethepoet<1.0.0",