MNT: (deps): Bump flake8-simplify from 0.12.0 to 0.14.0 in /ci

Bumps [flake8-simplify](https://github.com/MartinThoma/flake8-simplify) from 0.12.0 to 0.14.0.
- [Release notes](https://github.com/MartinThoma/flake8-simplify/releases)
- [Commits](MartinThoma/flake8-simplify@0.12.0...0.14.0)

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

ci/linting_requirements.txt

@@ -11,7 +11,7 @@ flake8-mutable==1.2.0
 flake8-pep3101==1.3.0
 flake8-print==4.0.0
 flake8-quotes==3.2.0
-flake8-simplify==0.12.0
+flake8-simplify==0.14.0
 pep8-naming==0.11.1
 
 flake8-rst-docstrings==0.0.14