chore: move cs-fixer to github actions (GoogleCloudPlatform#1735)

Author: bshaffer

.github/workflows/lint.yml

@@ -6,6 +6,18 @@ on:
   pull_request:
 
 jobs:
+  styles:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: '8.0'
+
+    - name: Run Script
+      run: testing/run_cs_check.sh
+
   staticanalysis:
     runs-on: ubuntu-latest
     steps: