Bump urllib3 from 1.26.14 to 1.26.18 in /docs

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.14 to 1.26.18.
- [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/1.26.14...1.26.18)

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

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

docs/requirements.txt

@@ -82,5 +82,5 @@ typing-extensions==4.4.0
     # via myst-parser
 uc-micro-py==1.0.1
     # via linkify-it-py
-urllib3==1.26.14
+urllib3==1.26.18
     # via requests