Upgrade stale action to v8 (#641)

Author: McGiverGim

.github/workflows/stale.yaml

@@ -9,7 +9,7 @@ jobs:
     name: 'Check and close stale issues'
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/stale@v3
+    - uses: actions/stale@v8
       with:
         repo-token: ${{ secrets.GITHUB_TOKEN }}
         operations-per-run: 30