chore(deps): bump date-holidays in /.github/workflows/holiday-generator (#1107)

Bumps [date-holidays](https://github.com/commenthol/date-holidays) from 3.26.8 to 3.26.9.
- [Changelog](https://github.com/commenthol/date-holidays/blob/master/CHANGELOG.md)
- [Commits](commenthol/date-holidays@v3.26.8...v3.26.9)

---
updated-dependencies:
- dependency-name: date-holidays
  dependency-version: 3.26.9
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]