Fix: Fail to pass Check changed files step of PR-CHECK workflow

Add "safe directory exception" to solve it.

.github/workflows/self-hosted-ci-pr-checker.yaml

@@ -33,6 +33,7 @@ jobs:
 
     - name: Check changed files
       run: |
+        git config --global --add safe.directory "$GITHUB_WORKSPACE"
         git fetch origin ${{ github.event.pull_request.base.ref }}:refs/remotes/origin/${{ github.event.pull_request.base.ref }}
         git diff --name-only origin/${{ github.event.pull_request.base.ref }} ${{ github.event.pull_request.head.sha }} > changed_files.txt
         cat changed_files.txt