Chore: Upgrade PHPStan to 2.x (#243)

Bumps phpstan/phpstan from 1.* to ^2.0 and fixes the 3 errors surfaced
at level 5:
- curl_setopt CURLOPT_RETURNTRANSFER value uses bool instead of int
- drop redundant assertIsArray/assertIsInt on already-typed returns

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: loks0n

composer.json

@@ -52,7 +52,7 @@
     "require-dev": {
         "doctrine/instantiator": "^1.5",
         "laravel/pint": "1.*",
-        "phpstan/phpstan": "1.*",
+        "phpstan/phpstan": "^2.0",
         "phpunit/phpunit": "^9.5.25",
         "swoole/ide-helper": "4.8.3"
     }

composer.lock

@@ -28,7 +28,6 @@ public function testCanGetHeaders()
         $this->assertEquals('value2', $this->request->getHeader('custom-new'));
 
         $headers = $this->request->getHeaders();
-        $this->assertIsArray($headers);
         $this->assertCount(2, $headers);
         $this->assertEquals('value1', $headers['custom']);
         $this->assertEquals('value2', $headers['custom-new']);
@@ -329,7 +328,6 @@ public function testCanGetSizeWithArrayHeaders()
 
         $size = $this->request->getSize();
 
-        $this->assertIsInt($size);
         $this->assertGreaterThan(0, $size);
     }
 }

tests/RequestTest.php

@@ -64,7 +64,7 @@ public function call(string $method, string $path = '', array $headers = [], arr
         $cookies = [];
 
         curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
-        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
         curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
         curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36');
         curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);