Add ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION

Author: jmlapre

.github/workflows/PR_clang-format_test.yml

@@ -61,6 +61,8 @@ jobs:
 #   Checkout this users SST-core repo/branch
     - name: Checkout Users SST-Core source
       uses: actions/checkout@v7
+      env:
+        ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
       with:
         path: ./sst-core_source
         ref: ${{ github.event.pull_request.head.sha }}