Update secp256k1 subtree to latest upstream + adapt API

The new schnorrsig API requires changing a few arguments.

src/pubkey.cpp

@@ -191,7 +191,7 @@ bool XOnlyPubKey::VerifySchnorr(const uint256& msg, Span<const unsigned char> si
     assert(sigbytes.size() == 64);
     secp256k1_xonly_pubkey pubkey;
     if (!secp256k1_xonly_pubkey_parse(secp256k1_context_verify, &pubkey, m_keydata.data())) return false;
-    return secp256k1_schnorrsig_verify(secp256k1_context_verify, sigbytes.data(), msg.begin(), &pubkey);
+    return secp256k1_schnorrsig_verify(secp256k1_context_verify, sigbytes.data(), msg.begin(), 32, &pubkey);
 }
 
 static const CHashWriter HASHER_TAPTWEAK = TaggedHash("TapTweak");