Bump urllib3 from 2.4.0 to 2.6.0 in /ci

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.4.0 to 2.6.0.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@2.4.0...2.6.0)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.6.0
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

ci/requirements-docs.txt

@@ -44,5 +44,5 @@ sphinx==1.8.5
     # via -r requirements-docs.in
 sphinxcontrib-websupport==1.1.0
     # via sphinx
-urllib3==2.4.0
+urllib3==2.6.0
     # via requests