Add 'Stale PRs' GH action to label and close inactive community PRs

[cbbayburt]

Add "Stale PRs" GH action to label and close inactive community PRs.

The action runs daily at 01:00 UTC to label any PR that is inactive for 60 days with Stale label.

After further 10 days, the action closes the PR and deletes its branch. The author has the chance to update the PR or simply remove the Stale label to unmark the PR for closing.

If needed, we can extend the action to issues as well.

Check out https://github.com/actions/stale for the full range of options this action supports.

Changelogs

Make sure the changelogs entries you are adding are compliant with https://github.com/uyuni-project/uyuni/wiki/Contributing#changelogs and https://github.com/uyuni-project/uyuni/wiki/Contributing#uyuni-projectuyuni-repository

If you don't need a changelog check, please mark this checkbox:

• No changelog needed

If you uncheck the checkbox after the PR is created, you will need to re-run changelog_test (see below)

Re-run a test

If you need to re-run a test, please mark the related checkbox, it will be unchecked automatically once it has re-run:

• Re-run test "changelog_test"
• Re-run test "backend_unittests_pgsql"
• Re-run test "java_pgsql_tests"
• Re-run test "schema_migration_test_pgsql"
• Re-run test "susemanager_unittests"
• Re-run test "javascript_lint"
• Re-run test "spacecmd_unittests"

[agraul]

In the announcement email / discussion for this we should probably clarify how "community" contributors can remove the "stale" label. Some users will know it from other GH repositories, but maybe not everyone does.

[renner]

Thanks a lot @cbbayburt, let's give it a try!

[renner]

This might not be possible in case of a fork, I guess, but community PRs would probably mostly be created from forks? In any case I am not completely sure if we wanted to delete any branches automatically, that could be painful in case a PR is closed accidentally if for example a person is on a longer leave or similar.

[cbbayburt]

Otherwise, we'll have to deal with all the zombie branches manually and that's a bit frustrating because we'll need to ping people, read through a lot of commit history etc. to be able to safely delete them.

AFAIK, GH backs up deleted branch heads so it should be possible to restore them.

Forked branches won't be deleted with this action, but since they're not in our domain, we shouldn't care about them. This setting is only meant as a cleanup for branches created in our repo, so it's only relevant for PRs from us.

[renner]

Do I understand correctly that when removing the stale label there will be another 60 days before this message will be added again?

[cbbayburt]

True, any kind of activity, including removing the label or simply commenting on the PR will reset the timer to 0.

[renner]

Do we really want to consider only community PRs? From my perspective we could include org members' PRs as well, so we also get a better feeling of how this automation "feels" if you are the author.