Format group_delete_command.dart

Fixes CI that started failing after adding dart format check.

Author: friebetill

lib/src/commands/group/group_delete_command.dart

@@ -30,13 +30,11 @@ class GroupDeleteCommand extends Command<void> {
   String get name => 'delete';
 
   @override
-  String get description =>
-      'Delete one or more groups. '
+  String get description => 'Delete one or more groups. '
       'Cards keep existing (groupId is unassigned).';
 
   @override
-  String get invocation =>
-      'space group delete <group-id> [<group-id>...] '
+  String get invocation => 'space group delete <group-id> [<group-id>...] '
       '[--force] [--dry-run]';
 
   @override