feat(ci): add stale branch workflow

[rjan90]

Proposed Changes

Add a workflow that marks stale branches and deletes stale branches:

• Branches are marked as stale after 180 days without no commits.
• Branch that have been inactive for 360 days is deleted.
• Has no protection rules.
• Exclude any branch that starts with 'release/miner' as these have no branch protection rules (ref)
• Is not the default branch

Checklist

Before you mark the PR ready for review, please make sure that:

• Commits have a clear commit message.
• PR title conforms with contribution conventions
• Update CHANGELOG.md or signal that this change does not need it per contribution conventions
• New features have usage guidelines and / or documentation updates in
  • Lotus Documentation
  • Discussion Tutorials
• Tests exist for new functionality or change in behavior
• CI is green

[BigLep]

I'm good to merge, but a couple of questions coming to mind:

1. What does denoting a branch as "stale" do?
2. What kind of communication is there that a branch is about to be deleted?

[rvagg]

let's land it with dry-run and observe the output the first time it runs and see if there are any surprises

[rjan90]

Agree on landing it with dry-run initially so that we can inspect the logs of the workflow firs. After diving deeper into the workflow today to answer some of Steve's questions, it also seems like an initial manual cleanup of the branches would be the best approach before landing this workflow, as well as some additional parameter tweaks:

• The difference between GitHub's definition of a stale branch and this workflows definition of a stale branch, is that once a branch is defined as stale by this bot (the days-before-stale param):
  • It creates a GH issue in the repo and tags the author saying that their branch is stale, and that it will be closed in (days-before-stale - days-before-delete)
  • If the author deletes, or add branch protection, their stale branch on their own, the issue will be closed automatically. If the author does not delete their stale branch, their branch will be deleted after the XY-amount of days from issue creation to deletion.

Given that we have 600+ branches, and most of these branches already are stale, it could quickly get a bit spammy without a initial cleanup, although the max amount of of stale branch issues that can exist at the same time is 20.

I will start with the manual cleanup, and then tweak the parameters.

[BigLep]

All sounds good @rjan90 . Also, I think it probably makes sense to document what some of the default are in the workflow (e.g., protoected branches excluded) or just add the value explicitly in so it's self documenting.

[rjan90]

I have updated the workflow with comments and explicitly set defaults to make it more self-descriptive. The 'dry-run' option has been set to true, allowing us to observe the behavior first.

Additionally, I have completed an initial cleanup of old branches, reducing the total from 647 to 161.