refactor: Make eventupdate null safe

lib/src/utils/event_update.dart

@@ -1,4 +1,3 @@
-// @dart=2.9
 /*
  *   Famedly Matrix SDK
  *   Copyright (C) 2019, 2020, 2021 Famedly GmbH
@@ -46,7 +45,12 @@ class EventUpdate {
   // the order where to stort this event
   final double sortOrder;
 
-  EventUpdate({this.roomID, this.type, this.content, this.sortOrder});
+  EventUpdate({
+    required this.roomID,
+    required this.type,
+    required this.content,
+    required this.sortOrder,
+  });
 
   Future<EventUpdate> decrypt(Room room, {bool store = false}) async {
     if (content['type'] != EventTypes.Encrypted ||

test/encryption/key_verification_test.dart

@@ -56,6 +56,7 @@ EventUpdate getLastSentEvent(KeyVerification req) {
     },
     type: EventUpdateType.timeline,
     roomID: req.room.id,
+    sortOrder: DateTime.now().millisecondsSinceEpoch.toDouble(),
   );
 }
 
@@ -461,6 +462,7 @@ void main() {
         },
         type: EventUpdateType.timeline,
         roomID: req2.room.id,
+        sortOrder: DateTime.now().millisecondsSinceEpoch.toDouble(),
       ));
       expect(req2.state, KeyVerificationState.error);