Bump requests from 2.22.0 to 2.31.0 in /app

Bumps [requests](https://github.com/psf/requests) from 2.22.0 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@v2.22.0...v2.31.0)

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

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

Author: dependabot[bot]

app/requirements.txt

@@ -6,7 +6,7 @@ flake8==3.7.9
 joblib==0.14.1
 lxml==4.5.0
 pytest==5.1.1
-requests==2.22.0
+requests==2.31.0
 scikit-learn==0.22.2.post1
 toolz==0.10.0
 urllib3==1.25.3