mod+keychain+lntest: bump btcd to version with tweak fix

This commit bumps to the latest version of btcd that fixes a key
mutation issue when signing for Taproot outputs.

go.mod

@@ -3,8 +3,8 @@ module github.com/lightningnetwork/lnd
 require (
 	github.com/NebulousLabs/go-upnp v0.0.0-20180202185039-29b680b06c82
 	github.com/Yawning/aez v0.0.0-20211027044916-e49e68abd344
-	github.com/btcsuite/btcd v0.23.3
-	github.com/btcsuite/btcd/btcec/v2 v2.2.1
+	github.com/btcsuite/btcd v0.23.4
+	github.com/btcsuite/btcd/btcec/v2 v2.2.2
 	github.com/btcsuite/btcd/btcutil v1.1.2
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.5
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.0.1