ci: fix generate-chart-schema job

.github/workflows/helm-release.yaml

@@ -22,19 +22,22 @@ jobs:
         run: |
           make helm-schema
 
-      - name: Branch
+      - name: Git diff
+        id: git-diff
+        run: |
+          git diff --exit-code
+          if [ $? -eq 0 ]; then
+            echo "::set-output name=changes::false"
+          else
+            echo "::set-output name=changes::true"
+          fi
+
+      - name: "Commit changes and make PR"
+        if: steps.git-diff.outputs.changes == 'true'
         run: |
           git checkout -b helm/schema-update
           git add charts/k6-operator/values.schema.json
-          git diff --cached | tee diff.file
-          echo "WC_DIFF=$(wc -c < diff.file)" >> "$GITHUB_OUTPUT"
-          wc -c < diff.file
-          cat diff.file
 
-      - name: "Make PR"
-        if: ${{ steps.branch.WC_DIFF }} > 0
-        run: |
-          echo "diff ${{ steps.branch.WC_DIFF }}"
           git config user.name "github-actions[bot]"
           git config user.email "41898282+github-actions[bot]@users.noreply.github.com"