Add php-cs check

Signed-off-by: Julius Härtl <jus@bitgrid.net>

.github/workflows/lint.yml

@@ -26,6 +26,22 @@ jobs:
       - name: Lint
         run: composer run lint
 
+  php-cs-fixer:
+    name: php-cs check
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@master
+    - name: Set up php
+      uses: shivammathur/setup-php@master
+      with:
+        php-version: 7.4
+        coverage: none
+    - name: Install dependencies
+      run: composer i
+    - name: Run coding standards check
+      run: composer run cs:check
+
   node:
     runs-on: ubuntu-latest