fix: make the working barrier on settings page dismissible

Barrier is dismissible because the SettingsCubit.toggleAutostart() method
can fail for Flatpak, and for some reason we can't catch the error.

This way, the user can dismiss the barrier instead of being stuck.

Resolves #202

lib/settings/settings_page.dart

@@ -13,7 +13,13 @@ import 'settings.dart';
 void _showLoadingDialog(BuildContext context) {
   showDialog(
     context: context,
-    barrierDismissible: false,
+    // Barrier is dismissible because the SettingsCubit.toggleAutostart() method
+    // can fail for Flatpak, and for some reason we can't catch the error.
+    //
+    // This way, the user can dismiss the barrier instead of being stuck.
+    //
+    // https://github.com/Merrit/nyrna/issues/202
+    barrierDismissible: true,
     builder: (context) {
       // If working is already false because it was a quick operation, we don't
       // need to show the dialog.