FIX: allows to query a username made of integers (#25815)

If a user had `123456789` as username, it could be passed to the query as a number and the query would fail as it expects a string.

Also applies the same fix to groups.

plugins/chat/app/queries/chat/users_from_usernames_and_groups_query.rb

@@ -9,8 +9,8 @@ module Chat
         .where(user_options: { chat_enabled: true })
         .where(
           "username IN (?) OR (groups.name IN (?) AND group_users.user_id IS NOT NULL)",
-          usernames,
-          groups,
+          usernames&.map(&:to_s),
+          groups&.map(&:to_s),
         )
         .where.not(id: excluded_user_ids)
         .distinct