composer.json: Drop require-dev support for phpstan 1

Fixes #1494

Author: reedy

composer.json

@@ -18,12 +18,12 @@
     "require-dev": {
         "phpunit/phpunit": "^10.5|^11.5|^12.0",
         "laminas/laminas-diactoros": "^3.5",
-        "phpstan/phpstan": "^1.12|^2.0",
-        "phpstan/phpstan-phpunit": "^1.3.15|^2.0",
+        "phpstan/phpstan": "^2.0",
+        "phpstan/phpstan-phpunit": "^2.0",
         "roave/security-advisories": "dev-master",
         "phpstan/extension-installer": "^1.3.1",
-        "phpstan/phpstan-deprecation-rules": "^1.1.4|^2.0",
-        "phpstan/phpstan-strict-rules": "^1.5.2|^2.0",
+        "phpstan/phpstan-deprecation-rules": "^2.0",
+        "phpstan/phpstan-strict-rules": "^2.0",
         "slevomat/coding-standard": "^8.14.1",
         "php-parallel-lint/php-parallel-lint": "^1.3.2",
         "squizlabs/php_codesniffer": "^3.8"