Fixed InterfaceGeneratorTest

Author: VladimirZaets

lib/internal/Magento/Framework/Code/Test/Unit/_files/app/code/Magento/SomeModule/Model/SevenInterface.php

@@ -45,9 +45,7 @@ public static function testMethod1(array &$data = []);
      */
     public function testMethod2($data = 'test_default', $flag = true);
 
-    /**
-     * @return mixed
-     */
+    
     public function testMethod3();