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

Reviewed-on: #64

lib/models/room_summary.dart

@@ -1,22 +1,24 @@
 import "package:freezed_annotation/freezed_annotation.dart";
 import "package:nexus/models/content/create.dart";
 import "package:nexus/models/join_rule.dart";
+
 part "room_summary.freezed.dart";
 part "room_summary.g.dart";
 
-@freezed
-abstract class RoomSummary with _$RoomSummary {
-  const factory RoomSummary({
-    required String roomId,
-    @JsonKey(name: "num_joined_members") required int joinedMembers,
-    JoinRule? joinRule,
-    String? name,
-    Uri? avatarUrl,
-    String? canonicalAlias,
-    String? topic,
-    String? roomVersion,
-    @JsonKey(unknownEnumValue: RoomType.room) RoomType? roomType,
-  }) = _RoomSummary;
+@Freezed(toJson: false, fromJson: false)
+@JsonSerializable()
+class const RoomSummary({
+  required final String roomId,
+  @JsonKey(name: "num_joined_members") required final int joinedMembers,
+  final JoinRule? joinRule,
+  final String? name,
+  final Uri? avatarUrl,
+  final String? canonicalAlias,
+  final String? topic,
+  final String? roomVersion,
+  @JsonKey(unknownEnumValue: RoomType.room) final RoomType? roomType,
+}) with _$RoomSummary {
+  Map<String, Object?> toJson() => _$RoomSummaryToJson(this);
 
   factory RoomSummary.fromJson(Map<String, Object?> json) =>
       _$RoomSummaryFromJson(json);