feat: add GH action for closing stale prs and issues

[DianaLease]

Closes #

Changes

• Marks issues as stale after 60 days of inactivity and closes 10 days later.
• Marks PRs as stale after 15 days of inactivity and closes 10 days later.
• Exempts anything in v4.0 milestone from being closed
• Uses https://github.com/marketplace/actions/close-stale-issues

Flags

• Please provide opinions on the timing for when an issue/PR is stale or closed. I used my best judgement here but would like to hear from the community. Also anything else we should exempt besides the v4.0 milestone items.

Screenshots or Video

Related Issues

• Issue Encourage activity on inactive PRs & issues / cleanup old ones technical-steering-committee#52
• Pull Request #

Author Checklist

• Ensure you provide a DCO sign-off for your commits using the --signoff option of git commit.
• Vital features and changes captured in unit and/or integration tests
• Commits messages follow AP format
• Extend the documentation, if necessary
• Merging to main from fork:branchname