Bump the llvm-docs-requirements group in /llvm/docs with 4 updates

Bumps the llvm-docs-requirements group in /llvm/docs with 4 updates: [certifi](https://github.com/certifi/python-certifi), [charset-normalizer](https://github.com/jawah/charset_normalizer), [idna](https://github.com/kjd/idna) and [packaging](https://github.com/pypa/packaging).


Updates `certifi` from 2026.2.25 to 2026.4.22
- [Commits](certifi/python-certifi@2026.02.25...2026.04.22)

Updates `charset-normalizer` from 3.4.6 to 3.4.7
- [Release notes](https://github.com/jawah/charset_normalizer/releases)
- [Changelog](https://github.com/jawah/charset_normalizer/blob/master/CHANGELOG.md)
- [Commits](jawah/charset_normalizer@3.4.6...3.4.7)

Updates `idna` from 3.11 to 3.13
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](kjd/idna@v3.11...v3.13)

Updates `packaging` from 26.0 to 26.2
- [Release notes](https://github.com/pypa/packaging/releases)
- [Changelog](https://github.com/pypa/packaging/blob/main/CHANGELOG.rst)
- [Commits](pypa/packaging@26.0...26.2)

---
updated-dependencies:
- dependency-name: certifi
  dependency-version: 2026.4.22
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: llvm-docs-requirements
- dependency-name: charset-normalizer
  dependency-version: 3.4.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: llvm-docs-requirements
- dependency-name: idna
  dependency-version: '3.13'
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: llvm-docs-requirements
- dependency-name: packaging
  dependency-version: '26.2'
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: llvm-docs-requirements
...

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Author: dependabot[bot]