Adding php compatibility checking

.github/workflows/linting.yaml

@@ -1,7 +1,10 @@
 ---
 name: Linting jobs
 
-on: [push]
+# yamllint disable-line rule:truthy
+on:
+  - push
+  - pull_request
 
 jobs:
   validate-composer:
@@ -42,3 +45,12 @@ jobs:
       - uses: actions/checkout@v1
       - name: Check markdown
         uses: pipeline-components/remark-lint@master
+
+  php-compitibility:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v1
+      - name: Check php compatibility
+        uses: pipeline-components/php-codesniffer@master
+        with:
+          options: "-s -p --colors --extensions=php --standard=PHPCompatibility --runtime-set testVersion 5.3-7.4"