This one doesn't require having shellcheck installed (it's bundled in
the Python package).

Convert them to the jUnit format and add them as a report.

- Update pre-commit checks.
- Replace Travis CI with GitLab CI.
- Address new warnings from pre-commit checks.

Update links accordingly.

- Corrected setup and teardown functions (didn't read the documentation correctly, should be a shell function not a test).

- Fix issue when diff is empty.
- Forgot --stdout in patch generation.
- Fix issue when it's the same branch.