message: refactor(core): convert publicKey to Buffer at callsite
  The utxolib will remove support for hex-encoded pubkeys
  Issue:
diff: @@ -1295,7 +1295,10 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  if (transaction.network !== this.network) {
  throw new Error(`network mismatch`);
  }
  - return utxolib.bitgo.verifySignature(transaction, inputIndex, amount, verificationSettings);
  + return utxolib.bitgo.verifySignature(transaction, inputIndex, amount, {
  + signatureIndex: verificationSettings.signatureIndex,
  + publicKey: verificationSettings.publicKey ? Buffer.from(verificationSettings.publicKey, 'hex') : undefined,
  + });
  }
  /**
  