Add workflow that is triggered after a successful dependabot PR

[OptimumCode]

The idea of the workflow is the following:

• PR from dependabot passes all checks and gets merged into the main branch;
• The new workflow is triggered (according to the documentation, we will be in the context of the main branch). Based on test runs - the PR commit is already there;
• Job checks out the branch, builds the image, and uploads it to the packages.

The if condition ensures that only successful PR from dependabot triggers the build.

The concurrency group ensures that only the latest PR from dependabot produces an image.

[OptimumCode]

Hi @Julian! I hope you don't mind if I merge changes without your review (to make sure that they work as expected - until workflow is merged to the main, it cannot be tested).
We can discuss/modify the workflow afterward.

[Julian]

I don't mind at all and appreciate you moving quick!!