Bump requests-mock-flask from 2021.7.10.0 to 2021.12.13 in /requirements

Bumps [requests-mock-flask](https://github.com/adamtheturtle/requests-mock-flask) from 2021.7.10.0 to 2021.12.13.
- [Release notes](https://github.com/adamtheturtle/requests-mock-flask/releases)
- [Changelog](https://github.com/adamtheturtle/requests-mock-flask/blob/master/CHANGELOG.rst)
- [Commits](adamtheturtle/requests-mock-flask@2021.07.10.0...2021.12.13)

---
updated-dependencies:
- dependency-name: requests-mock-flask
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements/dev-requirements.txt

@@ -24,7 +24,7 @@ pyroma==3.2  # Packaging best practices checker
 pytest-cov==3.0.0  # Measure code coverage
 pytest-envfiles==0.1.0  # Use files for environment variables for tests
 pytest==6.2.5  # Test runners
-requests-mock-flask==2021.7.10.0
+requests-mock-flask==2021.12.13
 sphinx-autodoc-typehints==1.12.0
 sphinx_paramlinks==0.5.2
 sphinxcontrib-httpdomain==1.8.0