doctr: 403 client error on api.github.com

I am trying to set up doctr on a new repo following the instructions in the readme. I have the latest version of doctr (1.7.3).

After I enter my authentication code, I get a 403 Client Error.

$ doctr configure
Welcome to Doctr.

We need to ask you a few questions to get you on your way to automatically
deploying from Travis CI to GitHub pages.

What is your GitHub username? rabernat
Enter the GitHub password for rabernat: 
A two-factor authentication code is required: sms
Authentication code: ******
Traceback (most recent call last):
  File "/Users/rpa/miniconda3/envs/geo_scipy/bin/doctr", line 6, in <module>
    sys.exit(doctr.__main__.main())
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/doctr/__main__.py", line 517, in main
    return process_args(get_parser(config=config))
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/doctr/__main__.py", line 249, in process_args
    return args.func(args, parser)
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/doctr/__main__.py", line 383, in configure
    login_kwargs = GitHub_login()
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/doctr/local.py", line 141, in GitHub_login
    return GitHub_login(username=username, password=password, OTP=OTP, headers=headers)
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/doctr/local.py", line 145, in GitHub_login
    r.raise_for_status()
  File "/Users/rpa/miniconda3/envs/geo_scipy/lib/python3.6/site-packages/requests/models.py", line 935, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 403 Client Error: Forbidden for url: https://api.github.com/

I am totally stuck on this issue! Any help would be greatly appreciated.