add stale PR bot

[RayBB]

On a call today with @lokesh @mekarpeles and @cdrini we discussed adding a bot to help nudge PRs that are waiting on submitter input.

The goal here is twofold:

1. Reduce the burden on maintainers
2. Improve the experience of contributing to Open Library's codebase

How this does this:

1. Maintainers won't have the cogitative overhead of looking through their many assigned issues and having to follow up with folks who didn't respond to feedback yet. Instead, when they label an issue as Needs: Submitter Input they know the process will be taken care of for them to nudge the contributor.
2. If you're a contributor this means that if staff gives you feedback and you miss it or forget it you'll have two nice automated reminders at reasonable intervals. First, a warning after one week. All you have to do is comment with your intention to work on it or push up a change.

Another benefit of this is when PRs are automatically closed with no activity is that this should make it easier for folks to find issues to work on that have been stale.

In practice this is a rather minor and incremental change to our workflow.

At present only 4 PRs would get a message encouraging them to follow up:

• fix(docker): add --no-install-recommends to apt-get installs (#2656) #12177 - Has feedback to be addressed as well
• Feat: Added Continue Reading Carousel on Homepage #11562 - Has feedback that should be addressed
• Use our Wikidata IDs for reading stat demographics #10718 - which does have changes requested by the reviewer but ALSO a question by the submitter. So this case, it would hopefully encourage response from both parties to follow up
• Add avatars for followers feature #9415 - I already sent a reminder here earlier this year

It may seem like if it effects so few PRs then why does it matter?

1. There have been nearly 100 PRs that have been closed (not merged) while having this label.
2. This is somewhat of a new workflow that can be expanded upon. If maintainers know this will happen it makes them more likely to use the label. In the future we could also automatically apply the submitter input label when maintainers request changes on a PR.

I want to emphasize, that this is an experiment to help us deal with many new contributors and an enormous backlog of PRs to review. It may seem a little impersonal to have this added but in the big picture it should give make more time having those important connections and conversations instead of just asking someone to please follow up. As such, we can always revert this if it turns out to be too noisy or problematic.

Prior Art

This complements our existing pm_stale_ticket_labeler.yml workflow, which silently labels assigned issues as Needs: Review Assignee after 14 days of inactivity (but never closes anything). This new workflow takes the next step by actually following up with PR authors and closing when there's no response.

Again, I'll emphasize there's a lot of possibilities here like maybe in the future we should unassign them from the issue when we close the PR. However, we can keep it as baby steps.

Technical

Testing

Screenshot

Stakeholders

[mekarpeles]

I agree that it nudge is important but I don't think we want to close it after 7 days

[mekarpeles]

X

[RayBB]

It's a bit confusing, but this is, indeed, closing it seven days after it has been labeled as "stale"

https://github.com/actions/stale?tab=readme-ov-file#days-before-close

The idle number of days before closing the stale issues or the stale pull requests (due to the stale label).
The issues or the pull requests will be closed if the last update (based on GitHub issue field updated_at) is older than the idle number of days.
Since adding the stale label will alter the last update date, we can calculate the number of days from this date.

[RayBB]

@mekarpeles I updated this to not close any issues. Just add a comment to them.