go.mod: update btcec dep

To include the update to the musig2 Session which allows the aggregate
nonce for the session to be registered instead of requiring the
individual nonces to be registered.

go.mod

@@ -5,7 +5,7 @@ require (
 	github.com/Yawning/aez v0.0.0-20211027044916-e49e68abd344
 	github.com/andybalholm/brotli v1.0.4
 	github.com/btcsuite/btcd v0.24.3-0.20250318170759-4f4ea81776d6
-	github.com/btcsuite/btcd/btcec/v2 v2.3.4
+	github.com/btcsuite/btcd/btcec/v2 v2.3.6
 	github.com/btcsuite/btcd/btcutil v1.1.5
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.8
 	github.com/btcsuite/btcd/chaincfg/chainhash v1.1.0