Exit with non-zero exit code when files were changed

[t-animal]

Is your feature request related to a problem? Please describe.
In CI pipelines it would be handy to ensure that all imports are sorted. However, this requires checking for changes manually.

Describe the solution you'd like
If changes were done to any file, exit with exit code 1, otherwise exit code 0.

Describe alternatives you've considered
Checking if files have changed using git.

[github-actions]

👋 Hello! Thanks for submitting a issue 😄! @Matt-Gleich Will try to respond as soon as possible.

[gleich]

Ahh, this is a good idea! As a quick fix for your CI, you can just run the following command after running import_sorter: git diff --exit-code

[gleich]

Released! Check the README.md for the updated docs!