Add lint action

Author: fetzi

.github/workflows/lint.yml

@@ -0,0 +1,36 @@
+name: lint
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+
+    strategy:
+            fail-fast: true
+            matrix:
+                php: [7.2 7.3 7.4]
+
+    runs-on: ubuntu-latest
+    name: PHP@${{ matrix.php }}
+
+    steps:
+    - uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        tools: pecl
+        extensions: imagick
+
+    - uses: actions/checkout@v2
+
+    - name: Validate composer.json and composer.lock
+      run: composer validate
+
+    - name: Install dependencies
+      run: composer install --prefer-dist --no-progress --no-suggest
+
+    - name: Lint code
+      run: composer run-script lint