compatibility check

Author: DominicWatts

.github/workflows/php.yml

@@ -6,4 +6,6 @@ jobs:
     steps:
     - uses: actions/checkout@master
     - name: PHPCS
-      run: docker run --rm -v $PWD:/code:ro domw/phpcs phpcs --colors --standard=Magento2 --report=full,summary,gitblame --extensions=php,phtml ./
+      run: docker run --rm -v $PWD:/code:ro domw/phpcs phpcs --colors --standard=Magento2 --report=full,summary,gitblame --extensions=php,phtml ./
+    - name: compatibility
+      run: docker run --rm -v $PWD:/code:ro domw/phpcompatibility phpcs --standard=PHPCompatibility --runtime-set testVersion 5.6-7.3 --colors --warning-severity=0 --report=full,summary --extensions=php,phtml ./