[GH-3408] Add support for stale PR workflow

[ArnavBalyan]

Rationale for this change

• There are several PRs with no activity
• Add cleanup workflow to notify and eventually close PRs with no activity

What changes are included in this PR?

• 2 month warn duration and close in additional 1 month

Are there any user-facing changes?

• No

[ArnavBalyan]

cc @wgtmac@gszadovszky thanks :)

[Fokko]

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

[Fokko]

Thanks @ArnavBalyan for adding this, I think it would be good to get this in place 👍

[ArnavBalyan]

Thanks @Fokko!

[wgtmac]

Thanks for improving this!

[Fokko]

Thanks @ArnavBalyan for adding this, and thanks @wgtmac for the review 🚀

[ArnavBalyan]

Thanks @Fokko and @wgtmac!