test: remove unneeded return after $this->markTestSkipped()

Author: kenjis

tests/system/Images/BaseHandlerTest.php

@@ -34,8 +34,6 @@ protected function setUp(): void
     {
         if (! extension_loaded('gd')) {
             $this->markTestSkipped('The GD extension is not available.');
-
-            return;
         }
 
         // create virtual file system

tests/system/Images/GDHandlerTest.php

@@ -33,8 +33,6 @@ protected function setUp(): void
     {
         if (! extension_loaded('gd')) {
             $this->markTestSkipped('The GD extension is not available.');
-
-            return;
         }
 
         // create virtual file system

tests/system/Images/ImageMagickHandlerTest.php

@@ -34,8 +34,6 @@ protected function setUp(): void
     {
         if (! extension_loaded('imagick')) {
             $this->markTestSkipped('The ImageMagick extension is not available.');
-
-            return;
         }
 
         $this->root = WRITEPATH . 'cache/';