async connect(req, opts) {
    const combinedOpts = { ...this.constructorOpts, ...opts };
    return super.connect(req, combinedOpts);
  }
Patched version of HttpsProxyAgent to get around a bug that ignores options
such as ca and rejectUnauthorized when upgrading the proxied socket to TLS:
https://github.com/TooTallNate/proxy-agents/issues/194