Update pre-commit and devcontainer pins when present

[CasperKristiansson]

Summary

Extend detection so the action updates pinned Python versions inside .pre-commit-config.yaml (language_version) and .devcontainer/devcontainer.json (base images or features) when they reference CPython patch versions.

Why

Teams often pin tooling in pre-commit hooks and devcontainers. Leaving those untouched after a patch bump creates drift and confusion. Automating the updates keeps local environments aligned with CI.

What needs to happen

• Parse .pre-commit-config.yaml to locate language_version or hook-specific overrides that contain explicit patch versions.
• Detect devcontainer base images or features pointing to CPython tags and rewrite them conservatively.
• Add fixtures covering pre-commit and devcontainer scenarios, including negative tests for ranges.
• Document the expanded coverage in README and examples.

References

• Roadmap capabilities item: "Pre-commit + devcontainer coverage".

Acceptance criteria

• Running with defaults updates pre-commit language_version pins and devcontainer Python base images when present.
• Tests cover update and no-op paths.
• Documentation lists the new file types.