Drop use of comprimised action

https://www.stepsecurity.io/blog/harden-runner-detection-tj-actions-changed-files-action-is-compromised

Author: tstellar

.github/workflows/pr-code-format.yml

@@ -32,7 +32,7 @@ jobs:
 
       - name: Get changed files
         id: changed-files
-        uses: tj-actions/changed-files@v39
+        uses: step-security/changed-files@3dbe17c78367e7d60f00d78ae6781a35be47b4a1
         with:
           separator: ","
           skip_initial_fetch: true