Delete obsolete comment

diff --git a/src/handler/register_wallet.c b/src/handler/register_wallet.c
index 1734312..4bb3899 100644
--- a/src/handler/register_wallet.c
+++ b/src/handler/register_wallet.c
@@ -241,15 +241,6 @@ void handler_register_wallet(dispatcher_context_t *dc, uint8_t protocol_version)
 
     memcpy(response.wallet_id, wallet_id, sizeof(wallet_id));
 
-    // TODO: we might want to add external info to be committed with the signature (e.g.: app
-    // version).
-    //       This would allow newer versions of the app to invalidate an old signature if desired,
-    //       for example if a vulnerability is discovered in the registration flow of a previous
-    //       app. The response would be changed to:
-    //         <wallet_id> <metadata_len> <metadata> <hmac>
-    //       And the signature would be on the concatenation of the wallet id and the metadata.
-    //       The client must persist the metadata, together with the signature.
-
     if (!compute_wallet_hmac(wallet_id, response.hmac)) {
         SEND_SW(dc, SW_BAD_STATE);  // this should never fail
         return;