Auto close stale pull requests

This feature will automatically identify and close all stale pull requests.

This feature gives you the ability to define a time period (in weeks), then NeetoGit will automatically identify and close pull requests that were created before the specified duration.

You can also choose to set a label i.e. `Add label on close` that will be added to the pull requests before closing, however, it is completely optional.

If you want NeetoGit to ignore certain pull requests, even if they are stale, you can do so by setting a label in the ignore label for pull request field. Then, add the same label to the pull requests that you want to ignore.