Fixed undefined constant error when using PantherTestCaseTrait (#439)

* Introduced a new enum containing browser names

* Update Browser.php

* Referenced PantherTestCase::CHROME instead of static::CHROME

* Referenced PantherTestCase::CHROME instead of static::CHROME

* Fixed use of constant

Author: nusje2000

src/PantherTestCaseTrait.php

@@ -164,13 +164,13 @@ public function takeScreenshotIfTestFailed(): void
      */
     protected static function createPantherClient(array $options = [], array $kernelOptions = [], array $managerOptions = []): PantherClient
     {
-        $browser = ($options['browser'] ?? self::$defaultOptions['browser'] ?? static::CHROME);
+        $browser = ($options['browser'] ?? self::$defaultOptions['browser'] ?? PantherTestCase::CHROME);
         $callGetClient = \is_callable([self::class, 'getClient']) && (new \ReflectionMethod(self::class, 'getClient'))->isStatic();
         if (null !== self::$pantherClient) {
             $browserManager = self::$pantherClient->getBrowserManager();
             if (
-                (static::CHROME === $browser && $browserManager instanceof ChromeManager) ||
-                (static::FIREFOX === $browser && $browserManager instanceof FirefoxManager)
+                (PantherTestCase::CHROME === $browser && $browserManager instanceof ChromeManager) ||
+                (PantherTestCase::FIREFOX === $browser && $browserManager instanceof FirefoxManager)
             ) {
                 ServerExtension::registerClient(self::$pantherClient);
 
@@ -180,7 +180,7 @@ protected static function createPantherClient(array $options = [], array $kernel
 
         self::startWebServer($options);
 
-        if (static::CHROME === $browser) {
+        if (PantherTestCase::CHROME === $browser) {
             self::$pantherClients[0] = self::$pantherClient = Client::createChromeClient(null, null, $managerOptions, self::$baseUri);
         } else {
             self::$pantherClients[0] = self::$pantherClient = Client::createFirefoxClient(null, null, $managerOptions, self::$baseUri);