yuzu/main: Use static variant of QFile's exists()

There's no need to construct a QFile instance just to check for its
existence.

src/yuzu/main.cpp

@@ -1096,7 +1096,7 @@ void GMainWindow::OnTransferableShaderCacheOpenFile(u64 program_id) {
         tranferable_shader_cache_folder_path + DIR_SEP +
         QString::fromStdString(fmt::format("{:016X}", program_id)) + ".bin";
 
-    if (!QFile(transferable_shader_cache_file_path).exists()) {
+    if (!QFile::exists(transferable_shader_cache_file_path)) {
         QMessageBox::warning(this,
                              tr("Error Opening %1 File").arg(QString::fromStdString(open_target)),
                              tr("File does not exist!"));