Merge branch 'task/SDK-4691_pub_key_signature' into 'release/v8.0.1'

SDK-4691 Investigate public key signature verification failure [hotfix 8.0.1]

See merge request sdk/sdk!6125

Author: aabellagm

src/megaclient.cpp

@@ -15756,7 +15756,7 @@ error MegaClient::trackSignature(attr_t signatureType, handle uh, const std::str
     if (signatureType == ATTR_SIG_CU255_PUBK)
     {
         // retrieve public key whose signature wants to be verified, from cache
-        const UserAttribute* attribute = user->getAttribute(signatureType);
+        const UserAttribute* attribute = user->getAttribute(ATTR_CU25519_PUBK);
         if (!attribute || !attribute->isValid())
         {
             LOG_warn << "Failed to verify signature " << User::attr2string(signatureType) << " for user " << uid << ": CU25519 public key is not available";