Add automation to keep the pytest test matrix up-to-date with latest
Home Assistant Core releases:
1. **Weekly Automation**: New workflow updates test matrix automatically
2. **Version Fetcher**: Python script queries GitHub API for latest HA Core releases
3. **PR Creation**: Automatically creates PRs when new versions are available
## Benefits
- No more manual updates when new HA Core versions are released
- Automatic tracking of new HA Core releases
- Reduces maintenance burden
## Background
This builds on commit a982acb which fixed mypy-dev pinning. While upstream
now installs latest mypy-dev automatically, the test matrix versions still
need manual updates. This automation solves that remaining manual task.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
