ci: fix PHPStan errors (#412)

Author: dunglas

phpstan.neon

@@ -9,8 +9,6 @@ parameters:
 	ignoreErrors:
 		- message: '#.+#'
 		  path: tests/DummyKernel.php
-		# Expected
-		- '#Method Symfony\\Component\\Panther\\PantherTestCase::createPantherClient\(\) should return Symfony\\Component\\Panther\\Client but returns Symfony\\Component\\BrowserKit\\AbstractBrowser\|null\.#'
 		# False positive
 		- '#Call to an undefined method ReflectionType::getName\(\)\.#'
 		# To fix in PHP WebDriver

src/PantherTestCaseTrait.php

@@ -170,7 +170,7 @@ protected static function createPantherClient(array $options = [], array $kernel
                 (static::CHROME === $browser && $browserManager instanceof ChromeManager) ||
                 (static::FIREFOX === $browser && $browserManager instanceof FirefoxManager)
             ) {
-                return $callGetClient ? self::getClient(self::$pantherClient) : self::$pantherClient;
+                return $callGetClient ? self::getClient(self::$pantherClient) : self::$pantherClient; // @phpstan-ignore-line
             }
         }
 
@@ -186,7 +186,7 @@ protected static function createPantherClient(array $options = [], array $kernel
             static::bootKernel($kernelOptions); // @phpstan-ignore-line
         }
 
-        return $callGetClient ? self::getClient(self::$pantherClient) : self::$pantherClient;
+        return $callGetClient ? self::getClient(self::$pantherClient) : self::$pantherClient; // @phpstan-ignore-line
     }
 
     /**