fix versions in github workflow and add a lint-ci command

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
 
     strategy:
       matrix:
-        php-version: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1']
+        php-version: ['8.1']
 
     steps:
     - uses: actions/checkout@v2
@@ -24,5 +24,5 @@ jobs:
 
     - uses: ramsey/composer-install@v1
 
-    - run: composer lint
+    - run: composer lint-ci
     - run: composer test

composer.json

@@ -41,6 +41,9 @@
         "lint": [
             "php-cs-fixer fix -v"
         ],
+        "lint-ci": [
+            "php-cs-fixer fix -v --dry-run --stop-on-violation"
+        ],
         "test": [
             "XDEBUG_MODE=coverage phpunit"
         ]