message: feat(bitgo): added sdk version to constants call
  added sdk version to constants call
  stlx-14556
diff: @@ -478,6 +478,7 @@ export abstract class BitGoAPI {
  // scheme, so we need to use a raw superagent instance to do this request.
  // Proxy settings must still be respected however
  const resultPromise = superagent.get(this.url('/client/constants'));
  + resultPromise.set('BitGo-SDK-Version', this._version);
  const result = await (this._proxy ? resultPromise.proxy(this._proxy) : resultPromise);
  BitGoAPI._constants[env] = result.body.constants;
  