Bump flake8-requirements from 1.5 to 1.5.1 (#612)

Bumps [flake8-requirements](https://github.com/Arkq/flake8-requirements) from 1.5 to 1.5.1.
- [Release notes](https://github.com/Arkq/flake8-requirements/releases)
- [Commits](arkq/flake8-requirements@v1.5.0...v1.5.1)

---
updated-dependencies:
- dependency-name: flake8-requirements
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

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

Author: dependabot[bot]

requirements-dev.txt

@@ -3,7 +3,7 @@ flake8==3.9.2
 flake8-bandit==2.1.2
 flake8-bugbear==21.4.3
 flake8-import-order==0.18.1
-flake8-requirements==1.5
+flake8-requirements==1.5.1
 sphinx==4.0.2
 pep257==0.7.0
 -e .