Bump urllib3 from 2.2.1 to 2.6.0 in /docs/sphinx (#226)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.2.1 to 2.6.0.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](https://github.com/urllib3/urllib3/compare/2.2.1...2.6.0

)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.6.0
  dependency-type: indirect
...
Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/sphinx/requirements.txt

@@ -266,7 +266,7 @@ typing-extensions==4.11.0
     #   pygithub
     #   referencing
     #   sqlalchemy
-urllib3==2.2.1
+urllib3==2.6.0
     # via
     #   pygithub
     #   requests