pin skip-duplicate-actions

Author: gilesknap

.github/workflows/code.yml

@@ -18,7 +18,8 @@ jobs:
       should_skip: ${{ steps.skip_check.outputs.should_skip }}
     steps:
       - id: skip_check
-        uses: fkirc/skip-duplicate-actions@v4
+        # pinned to SHA for v4.0.0
+        uses: fkirc/skip-duplicate-actions@9d116fa7e55f295019cfab7e3ab72b478bcf7fdd
         with:
           concurrent_skipping: "always"