Bump mock from 4.0.3 to 5.1.0

Bumps [mock](https://github.com/testing-cabal/mock) from 4.0.3 to 5.1.0.
- [Changelog](https://github.com/testing-cabal/mock/blob/master/CHANGELOG.rst)
- [Commits](testing-cabal/mock@4.0.3...5.1.0)

---
updated-dependencies:
- dependency-name: mock
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

requirements-dev.txt

@@ -1,4 +1,4 @@
-mock == 4.0.3
+mock == 5.1.0
 pytest == 6.2.5
 pytest-cov == 3.0.0
 -r requirements.txt