add prs cache clean workflow

.github/workflows/prs-cache-clean.yml

@@ -0,0 +1,33 @@
+name: prs cache clean
+on:
+    pull_request:
+        types:
+            - closed
+
+jobs:
+    cleanup:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout
+              uses: actions/checkout@v4
+
+            - name: Cleanup
+              run: |
+                  gh extension install actions/gh-actions-cache
+
+                  REPO=${{ github.repository }}
+                  BRANCH="refs/pull/${{ github.event.pull_request.number }}/merge"
+
+                  echo "Fetching list of cache key"
+                  cacheKeysForPR=$(gh actions-cache list -R $REPO -B $BRANCH | cut -f 1 )
+
+                  ## Setting this to not fail the workflow while deleting cache keys. 
+                  set +e
+                  echo "Deleting caches..."
+                  for cacheKey in $cacheKeysForPR
+                  do
+                      gh actions-cache delete $cacheKey -R $REPO -B $BRANCH --confirm
+                  done
+                  echo "Done"
+              env:
+                  GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}