Bump requests from 2.27.1 to 2.31.0 in /doc/manual

Bumps [requests](https://github.com/psf/requests) from 2.27.1 to 2.31.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/main/HISTORY.md)
- [Commits](psf/requests@v2.27.1...v2.31.0)

---
updated-dependencies:
- dependency-name: requests
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

doc/manual/requirements.txt

@@ -20,7 +20,7 @@ Pygments==2.12.0
 pyparsing==3.0.9
 pytz==2022.1
 PyYAML==6.0
-requests==2.27.1
+requests==2.31.0
 six==1.16.0
 snowballstemmer==2.2.0
 soupsieve==2.3.2.post1