Updates phpstan/phpstan-phpunit dependency version

Replaces "2.0.x-dev" with "^2.0" for phpstan/phpstan-phpunit dependency to ensure compatibility with stable releases and improve dependency management.

Author: Vitexus

.openapi-generator/templates/composer.mustache

@@ -37,7 +37,7 @@
         "friendsofphp/php-cs-fixer": "^3.75",
         "ergebnis/composer-normalize": "^2.47",
         "ergebnis/php-cs-fixer-config": "^6.46",
-        "phpstan/phpstan-phpunit": "2.0.x-dev"
+        "phpstan/phpstan-phpunit": "^2.0"
     },
     "autoload": {
         "psr-4": {

composer.json

@@ -33,7 +33,7 @@
         "friendsofphp/php-cs-fixer": "^3.75",
         "ergebnis/composer-normalize": "^2.47",
         "ergebnis/php-cs-fixer-config": "^6.46",
-        "phpstan/phpstan-phpunit": "2.0.x-dev"
+        "phpstan/phpstan-phpunit": "^2.0"
     },
     "autoload": {
         "psr-4": {