move on with the migration

packages/stream_chat/lib/src/models/command.dart

@@ -7,9 +7,9 @@ part 'command.g.dart';
 class Command {
   /// Constructor used for json serialization
   Command({
-    this.name,
-    this.description,
-    this.args,
+    required this.name,
+    required this.description,
+    required this.args,
   });
 
   /// Create a new instance from a json
@@ -17,13 +17,13 @@ class Command {
       _$CommandFromJson(json);
 
   /// The name of the command
-  final String? name;
+  final String name;
 
   /// The description explaining the command
-  final String? description;
+  final String description;
 
   /// The arguments of the command
-  final String? args;
+  final String args;
 
   /// Serialize to json
   Map<String, dynamic> toJson() => _$CommandToJson(this);