exempt milestones from becoming stale [skip ci]

Author: Christopher Doris

Diff for: .github/workflows/stale.yaml

@@ -12,6 +12,7 @@ jobs:
     steps:
       - uses: actions/stale@v8
         with:
+          exempt-all-milestones: true
           days-before-issue-stale: 60
           stale-issue-message: >
             This issue has been marked as stale because it has been open for 60 days with no