chore: reduce require-dev

Author: phil-davis

composer.json

@@ -48,9 +48,6 @@
     "require-dev": {
         "friendsofphp/php-cs-fixer": "~2.17.1 || ^3.60",
         "phpstan/phpstan": "^0.12 || ^1.1",
-        "phpstan/phpstan-phpunit": "^1.4",
-        "phpstan/phpstan-strict-rules": "^1.6",
-        "phpstan/extension-installer": "^1.4",
         "phpunit/phpunit" : "^7.5 || ^8.5 || ^9.6"
     },
     "scripts": {
@@ -69,10 +66,5 @@
             "composer cs-fixer",
             "composer phpunit"
         ]
-    },
-    "config": {
-        "allow-plugins": {
-            "phpstan/extension-installer": true
-        }
     }
 }