⚙️ internal: actions/stale (#2252)

- Keep issues/prs open if they are assigned
- Keep issues open if labeled: `in-progress` or `planned`

## Type of change

**NONE: internal change**

.github/workflows/stale.yml

@@ -7,9 +7,11 @@ jobs:
  stale:
  runs-on: ubuntu-latest
  steps:
- - uses: actions/stale@v7
+ - uses: actions/stale@v8
  with:
  exempt-all-pr-milestones: true
+ exempt-issue-labels: in-progress, planned
+ exempt-all-assignees: true
  stale-issue-message: Message to comment on stale issues. If none provided, will not mark issues stale
  stale-issue-label: stale
  stale-pr-message: Message to comment on stale PRs. If none provided, will not mark PRs stale