chore: Follow up change own power level

lib/pages/user_bottom_sheet/user_bottom_sheet_view.dart

@@ -299,7 +299,10 @@ class UserBottomSheetView extends StatelessWidget {
                           BorderRadius.circular(AppConfig.borderRadius / 2),
                       color: Theme.of(context).colorScheme.onInverseSurface,
                       child: DropdownButton<int>(
-                        onChanged: user.canChangePowerLevel
+                        onChanged: user.canChangePowerLevel ||
+                                // Workaround until https://github.com/famedly/matrix-dart-sdk/pull/1765
+                                (user.room.canChangePowerLevel &&
+                                    user.id == user.room.client.userID)
                             ? controller.setPowerLevel
                             : null,
                         value: {0, 50, 100}.contains(user.powerLevel)

lib/widgets/permission_slider_dialog.dart

@@ -21,7 +21,7 @@ Future<int?> showPermissionChooser(
             return L10n.of(context)!.pleaseEnterANumber;
           }
           final level = int.tryParse(text);
-          if (level == null || level < 0) {
+          if (level == null) {
             return L10n.of(context)!.pleaseEnterANumber;
           }
           return null;