Stale Pull Requests?

[Steve Lawrence]

We have a relatively large number of stale pull requests open, some over 
4 years old. These clearly do not have high enough priority to push over 
the finish line, and many probably would take a decent amount of work 
just to update to compile with latest code base.

What are your thoughts on enabling something like 
https://github.com/actions/stale to automatically warn and close PR's 
that have gone without activity for some period of time? Most of the PRs 
have an associated bug, so we could add a link to the PR so that if 
someone does decide to revive the issue there is some record of past 
approaches.