chore: Follow up deduplicate events

lib/pages/chat_search/chat_search_page.dart

@@ -70,6 +70,16 @@ class ChatSearchController extends State<ChatSearchPage>
               result.$2,
             ),
           )
+          // Deduplication workaround for
+          // https://github.com/famedly/matrix-dart-sdk/issues/1831
+          .map(
+            (result) => (
+              <String, Event>{
+                for (final event in result.$1) event.eventId: event,
+              }.values.toList(),
+              result.$2,
+            ),
+          )
           .asBroadcastStream();
     });
   }