Debugging the deployment pipeline / Disable pushes to main #3123

It's probably an issue that so far only affects me, pushing to main ;).
For 1.4.2b6 I had some issues with the deploy pipeline, and being very sure about the problem -> fix, I pushed to main.
Then again,
and again.
While I was doing it, I of course knew it was wrong, but the excitement of a new release...

Main branch is now protected and I looked into better ways of doing debugging the deployment pipeline.
My main concern is that tags in general should not be removed, but also, with our package size, we cannot have an endless number of releases on cf (unfortunately).
But tags are used to trigger releases in the first place.

So that's what I came up with: I propose that in future, when debugging the deploy pipeline, to

1. Checkout a new branch
2. Change the destination label to debug
3. use tags a la 1.x.y.devN
4. Fix the problem
5. Revert the destination label change
6. Remove all .devN builds from ilastik-forge
7. cleanup branch, delete .devN tags
8. Merge into main
9. Tag on main branch -> release

the list could maybe become a PR template - I will probably forget that this list exists otherwise. But let's see where the discussion goes.