CI: remove stale assignments
Use a third-party GitHub Action to handle the claiming of issues. [See it in action.](https://github.com/afeld/pandas/issues/2#issuecomment-779635007)

It also handles automatically unassigning them after a period of inactivity, which is the more interesting part. The motivation here is that I bet there are a lot of issues where someone has used `take`, but the issue remains open without movement. [By default](https://github.com/JasonEtco/slash-assign-action#options), this Action will remove the assignment after 21 days. Open to suggestions about whether that should be longer or shorter.

- [ ] ~~closes #xxxx~~
- [ ] ~~tests added / passed~~
- [ ] ~~Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them~~
- [ ] ~~whatsnew entry~~

can we *also* accept `/take`?  Nice, thanks!

`take` is pretty commonly engrained in contributors' memory - would it be possible to delete the old workflow and replace it with this new one but make it trigger on 'take' instead of '/assign', so that nothing changes from the contributors' side but underneath this new workflow is triggered? From a pass through the source code of the Action, it _seems_ like `/action` is hard-coded.

https://github.com/JasonEtco/slash-assign-action/blob/842404647dfd10109c8c4feb3e776807eb5e2071/src/lib/comment-handler.ts#L8

Could submit a patch to make the slash command configurable, but based on the framework they are using, removing the leading slash would be harder.

If we feel strongly about sticking with `take`, could have the current Action do the assignment and use the same label as this new Action, and just rely on the new one for the cleanup. Thoughts? > could have the current Action do the assignment and use the same label as this new Action, and just rely on the new one for the cleanup

As in, if a user comments `take` then the issue will be assigned to them (by the existing workflow), and then the assignment will be removed after 21 days (by the new workflow)? If that's possible, sounds good.
Else, switching to `/assign` is also fine with me This pull request is stale because it has been open for thirty days with no activity. Please update or respond to this comment if you're still interested in working on this. @afeld is this ready? Not sure about this. The project seems like a [one-off](https://github.com/JasonEtco/slash-assign-action/graphs/contributors) development, I wouldn't expect it to be maintained.

And feels like implementing an action to unassign actions should be as easy as our assign action. Not against this, but I'd rather maintain couple of curl calls than someone else's typescript code for this. Appears like this PR has gone stale and ideally we'd want to just roll out own method for removing stale assignments. Going to close for now but let us know if you want to continue.