Update check-restricted-files.yaml

Author: ralfhandl

.github/workflows/check-restricted-files.yaml

@@ -22,8 +22,8 @@ jobs:
         run: |
           # TODO: skip if base.ref is main
 
-          git diff --exit-code --name-only ${{ github.event.pull_request.head.sha }} ${{ github.event.pull_request.base.sha }} -- schemas versions
-          if [[ $? -ne 0 ]]; then
+          changes = $(git diff --exit-code --name-only ${{ github.event.pull_request.head.sha }} ${{ github.event.pull_request.base.sha }} -- schemas versions)
+          if [[ $changes -ne 0 ]]; then
             echo This PR contains changes to files that should not be changed on ${{ github.event.pull_request.base.ref }}
             exit 1
           fi