crypto: Remove some stale TODOs.

matrix_sdk_crypto/src/olm/signing/pk_signing.rs

@@ -170,7 +170,6 @@ impl MasterSigning {
     }
 
     pub async fn sign_subkey<'a>(&self, subkey: &mut CrossSigningKey) {
-        // TODO create a borrowed version of a cross singing key.
         let subkey_wihtout_signatures = json!({
             "user_id": subkey.user_id.clone(),
             "keys": subkey.keys.clone(),

matrix_sdk_crypto/src/verification/sas/sas_state.rs

@@ -117,9 +117,6 @@ impl Default for AcceptedProtocols {
     }
 }
 
-// TODO implement expiration of the verification flow using the timeouts defined
-// in the spec.
-
 /// A type level state machine modeling the Sas flow.
 ///
 /// This is the generic struc holding common data between the different states