Bump urllib3 from 2.6.2 to 2.6.3 in /llvm/docs (#2973)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.6.2 to 2.6.3.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@2.6.2...2.6.3)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.6.3
  dependency-type: direct:production
...

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