chore(deps): refresh Python dependency lockfile

[alexb-splunk]

Summary

• refresh the complete uv.lock dependency graph
• update the reported idna, filelock, and virtualenv versions to remediated releases
• set Black's target version to Python 3.9 so formatter validation matches the package's supported floor

Validation

• uv lock --check --no-config
• lint and 12 tests on Python 3.13
• 12 tests on Python 3.9
• 12 tests on Python 3.14
• wheel and source distribution build

Release impact

This changes the development lockfile and formatter configuration only. Runtime dependency metadata and package behavior are unchanged, so this chore(deps) change should not publish a new package release.