I am deploying the workflow on my local repository to test this. Will report back

Yep!! It works properly.

@mmuetzel I assume you've tested it this as well. Should we wait for @siko1056 before merging or you think that we suffice?

I didn't test this much apart from feeding some input into that bash snippet locally.

I'd prefer if @siko1056 could have a look, too. There's also no rush for this. So, imho we could keep this open for a week or so.
If Kai didn't have time until then, we could still take a deeper look and decide on whether to merge...

Ok. Let's wait for @siko1056 's input as well. I did test it on a deployed version in my personal GitHub account and it seems to work (after pushing a commit to remove a yaml file, after a few refreshes, the Package Index wasn't listing the removed package, but I am not 100% confident about what the functionality should/would look like. I am not sure, whether merging a PR behaves differently, because on the actual deployment (this repo) we cannot push a commit, it has to be pulled as a PR. So let's wait a bit. packajoozle has been removed anyway.

Thank you for this PR, I will try it later this week.

Works like a charm @mmuetzel . Please merge 🙏

I made a local test commit that removes two packages, changes two packages and adds one package. It detects it all and would run the checks on the modified and new package only 👍

bash check.sh 
M       packages/bsltl.yaml
D       packages/chartjs.yaml
M       packages/image.yaml
D       packages/json.yaml
A       packages/new_package.yaml
CHANGED_PACKAGES=" bsltl  image  new_package "

Thank you both for the review.