Add php-cs-fixer ci job

.github/workflows/test.yml

@@ -44,6 +44,18 @@ jobs:
       - run: make all
         working-directory: tools
 
+  php-cs-fixer:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: 7.4
+      - name: Run php-cs-fixer
+        run: |
+          make php-cs-fixer
+        working-directory: legacy
+
   test-legacy:
     strategy:
       matrix: