chore(repo): add lints, update freezed, json_serializable

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat/test/src/core/models/channel_state_test.dart

@@ -48,8 +48,9 @@ void main() {
       final channelState = ChannelState(
         channel: ChannelModel.fromJson(j['channel']),
         members: [],
-        messages:
-            (j['messages'] as List).map((m) => Message.fromJson(m)).toList(),
+        messages: (j['messages'] as List<Map<String, dynamic>>)
+            .map(Message.fromJson)
+            .toList(),
         read: [],
         watcherCount: 5,
         pinnedMessages: [],

packages/stream_chat/test/src/core/models/filter_test.dart

@@ -123,7 +123,7 @@ void main() {
     test('custom', () {
       const key = 'testKey';
       const value = 'testValue';
-      const operator = '\$customOperator';
+      const operator = r'$customOperator';
       const filter = Filter.custom(operator: operator, key: key, value: value);
       expect(filter.key, key);
       expect(filter.value, value);