Add PHP workflow

Author: Pierstoval

.github/workflows/php.yml

@@ -0,0 +1,23 @@
+name: PHP
+
+on: [push]
+
+jobs:
+    build:
+
+        runs-on: ubuntu-latest
+
+        steps:
+            - uses: actions/checkout@v1
+
+            - name: Validate composer.json and composer.lock
+              run: composer validate
+
+            - name: Install dependencies
+              run: composer install --prefer-dist --no-progress --no-suggest
+
+            - name: PHPStan
+              run: make phpstan
+
+            - name: CS
+              run: make cs