qt/game_list: Give GameListSearchField::KeyReleaseEater a parent

This fixes a memory leak as KeyReleaseEater's destructor was never
called.

src/yuzu/game_list_p.h

@@ -330,7 +330,7 @@ public:
 private:
     class KeyReleaseEater : public QObject {
     public:
-        explicit KeyReleaseEater(GameList* gamelist);
+        explicit KeyReleaseEater(GameList* gamelist, QObject* parent = nullptr);
 
     private:
         GameList* gamelist = nullptr;