Move to Flutter 3.47, use the improvements that come with this (#64)

Reviewed-on: #64

lib/models/client_state.dart

@@ -1,16 +1,18 @@
 import "package:freezed_annotation/freezed_annotation.dart";
+
 part "client_state.freezed.dart";
 part "client_state.g.dart";
 
-@freezed
-abstract class ClientState with _$ClientState {
-  const factory ClientState({
-    required bool isInitialized,
-    required bool isLoggedIn,
-    required bool isVerified,
-    required String? userId,
-    required String? homeserverUrl,
-  }) = _ClientState;
+@Freezed(toJson: false, fromJson: false)
+@JsonSerializable()
+class const ClientState({
+  required final bool isInitialized,
+  required final bool isLoggedIn,
+  required final bool isVerified,
+  required final String? userId,
+  required final String? homeserverUrl,
+}) with _$ClientState {
+  Map<String, Object?> toJson() => _$ClientStateToJson(this);
 
   factory ClientState.fromJson(Map<String, Object?> json) =>
       _$ClientStateFromJson(json);