Misc: Use [[fallthrough]] attribute instead of comment to mark intentional fallthroughs

src/server/game/Entities/GameObject/GameObject.cpp

@@ -440,7 +440,7 @@ void GameObject::Update(uint32 diff)
                     break;
             }
         }
-        /* fallthrough */
+        [[fallthrough]];
         case GO_READY:
         {
             if (m_respawnCompatibilityMode)