fix: Update read receipt display

lib/views/chat.dart

@@ -60,8 +60,6 @@ class _ChatState extends State<Chat> {
 
   MatrixState matrix;
 
-  String seenByText = '';
-
   final AutoScrollController _scrollController = AutoScrollController();
 
   FocusNode inputFocus = FocusNode();
@@ -150,8 +148,6 @@ class _ChatState extends State<Chat> {
       () {
         filteredEvents =
             timeline.getFilteredEvents(collapseRoomCreate: _collapseRoomCreate);
-        seenByText =
-            room.getLocalizedSeenByText(context, timeline, filteredEvents);
       },
     );
   }
@@ -751,7 +747,15 @@ class _ChatState extends State<Chat> {
                                           )
                                         : Container()
                                 : i == 0
-                                    ? AnimatedContainer(
+                                    ? StreamBuilder(
+                                        stream: room.onUpdate.stream,
+                                        builder: (_, __) {
+                                          final seenByText =
+                                              room.getLocalizedSeenByText(
+                                                  context,
+                                                  timeline,
+                                                  filteredEvents);
+                                          return AnimatedContainer(
                                             height: seenByText.isEmpty ? 0 : 24,
                                             duration: seenByText.isEmpty
                                                 ? Duration(milliseconds: 0)
@@ -776,8 +780,8 @@ class _ChatState extends State<Chat> {
                                                 maxLines: 1,
                                                 overflow: TextOverflow.ellipsis,
                                                 style: TextStyle(
-                                              color:
+                                                  color: Theme.of(context)
-                                                  Theme.of(context).accentColor,
+                                                      .accentColor,
                                                 ),
                                               ),
                                             ),
@@ -786,6 +790,8 @@ class _ChatState extends State<Chat> {
                                               right: 8,
                                               bottom: 8,
                                             ),
+                                          );
+                                        },
                                       )
                                     : AutoScrollTag(
                                         key: ValueKey(