Add codequality.yml for GitHub Actions.

Author: john-shaffer

.github/workflows/codequality.yml

@@ -0,0 +1,44 @@
+name: codequality
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php: [7.3.9]
+
+    name: PHP-${{ matrix.php }} 
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Cache PHP dependencies
+      uses: actions/cache@v1
+      with:
+        path: vendor
+        key: ${{ runner.OS }}-build-${{ hashFiles('**/composer.lock') }}
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite, bcmath, soap, intl, gd, exif, iconv, imagick
+        coverage: none
+
+    - name: Validate Composer
+      run: composer validate --strict
+
+    - name: Install PHP dependencies
+      run: composer install --no-interaction --no-suggest
+
+    - name: Run our Linter and PHPStan
+      run: composer test