message: chore(core): add deprecation notice in bitcoin.ts
  Sadly we can't fully remove them just yet because there are a few
  legacy sites that use it.
  Issue:
diff: @@ -29,6 +29,7 @@ export function makeRandomKey(): utxolib.ECPair {
  return utxolib.ECPair.makeRandom({ network: getNetwork() });
  }
  +/** @deprecated - use bip32 package instead */
  function getKey(network?: utxolib.Network): utxolib.ECPair {
  network = network || getNetwork();
  const k = this.keyPair;
  @@ -40,16 +41,10 @@ function getKey(network?: utxolib.Network): utxolib.ECPair {
  return result;
  }
  +/** @deprecated - use bip32 package instead */
  utxolib.HDNode.prototype.getKey = getKey;
  -/**
  - * Derive a child HDNode from a parent HDNode and index. Uses secp256k1 to speed
  - * up public key derivations by 100x vs. bitcoinjs-lib implementation.
  - *
  - * @param {HDNode} hdnode parent HDNode
  - * @param {Number} index child index
  - * @returns {HDNode} derived HDNode
  - */
  +/** @deprecated - use bip32 package instead */
  function deriveFast(hdnode: utxolib.HDNode, index: number): utxolib.HDNode {
  // no fast path for private key derivations -- delegate to standard method
  if (!secp256k1 || hdnode.keyPair.d) {
  