build(deps): bump urllib3 from 1.26.12 to 1.26.18 in /docs (#7778)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.12 to 1.26.18.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.26.12...1.26.18)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Fabian Braun <fsbraun@gmx.de>

docs/requirements.txt

@@ -167,7 +167,7 @@ typing-extensions==4.9.0
     #   typing-inspect
 typing-inspect==0.9.0
     # via libcst
-urllib3==1.26.12
+urllib3==1.26.18
     # via requests
 wheel==0.38.3
     # via pip-tools