Add a missing PHPStan dependency (see contao#2543)

Description
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Commits
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288bc91 Add a missing PHPStan dependency

Author: leofeyer

composer.json

@@ -152,7 +152,8 @@
         "psr/event-dispatcher": "^1.0",
         "slam/phpstan-extensions": "^5.0",
         "symfony/browser-kit": "4.4.*",
-        "symfony/phpunit-bridge": "4.4.*"
+        "symfony/phpunit-bridge": "4.4.*",
+        "thecodingmachine/phpstan-strict-rules": "^0.12"
     },
     "extra": {
         "contao-manager-plugin": {

monorepo.yml

@@ -12,6 +12,7 @@ composer:
         contao/monorepo-tools: dev-master
         contao/phpstan: ^0.12
         slam/phpstan-extensions: ^5.0
+        thecodingmachine/phpstan-strict-rules: ^0.12
 
 repositories:
     core-bundle: