Messaging: Parse mentions.

src/routes/channels/group_remove_member.rs

@@ -58,6 +58,7 @@ pub async fn req(user: User, target: Ref, member: Ref) -> Result<()> {
                 id: member.id,
                 by: user.id,
             }),
+            None
         )
         .publish(&channel)
         .await