Bump requests from 2.20.0 to 2.31.0 in /source-code/chapter-3/python-app (#30)

Bumps [requests](https://github.com/psf/requests) from 2.20.0 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@v2.20.0...v2.31.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

source-code/chapter-3/python-app/requirements.txt

@@ -1,2 +1,2 @@
 praw==3.6.0
-requests==2.20.0
+requests==2.31.0