Tweak Travis config

.travis.yml

@@ -13,7 +13,6 @@ jobs:
     - before_script: composer install --no-interaction --prefer-dist $PREFER_LOWEST
       script: composer lint
       name: "Lint code"
-      php: 7.2.0
 
 script: composer test-ci
 before_script:

composer.json

@@ -31,7 +31,7 @@
         "dingo/api": "2.0.0-alpha1",
         "mockery/mockery": "^1.2.0",
         "league/fractal": "^0.17.0",
-        "phpstan/phpstan": "^0.9.0"
+        "phpstan/phpstan": "^0.9.0 || ^0.10.0 || ^0.11.15"
     },
     "suggest": {
         "league/fractal": "Required for transformers support",