ci: add cancel pr workflow (#1070)

.github/workflows/cancel-pr-workflow.yml

+name: Cancel PR Workflows on Merge
+
+on:
+  pull_request:
+    types:
+      - closed
+
+permissions:
+  actions: write
+
+jobs:
+  cancel:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.12.1
+        with:
+          workflow_id: all
+          access_token: ${{ secrets.GITHUB_TOKEN }}
+          ignore_sha: true
+          pr_number: ${{ github.event.pull_request.number }}