update noble secp256k1 and ensure we always return hex.

event.js

@@ -52,5 +52,7 @@ export function verifySignature(event) {
 }
 
 export async function signEvent(event, key) {
-  return secp256k1.schnorr.sign(getEventHash(event), key)
+  return Buffer.from(
+    await secp256k1.schnorr.sign(getEventHash(event), key)
+  ).toString('hex')
 }