Nightly wheels still failing

[ianhi]

most recently: https://github.com/zarr-developers/numcodecs/actions/runs/23176346328

with errors like this

           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 189, in urlopen
      return opener.open(url, data, timeout)
             ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 495, in open
      response = meth(req, response)
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 604, in http_response
      response = self.parent.error(
          'http', request, response, code, msg, hdrs)
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 533, in error
      return self._call_chain(*args)
             ~~~~~~~~~~~~~~~~^^^^^^^
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 466, in _call_chain
      result = func(*args)
    File "/Library/Frameworks/Python.framework/Versions/3.13/lib/python3.13/urllib/request.py", line 613, in http_error_default
      raise HTTPError(req.full_url, code, msg, hdrs, fp)
  urllib.error.HTTPError: HTTP Error 429: Too Many Requests
  Error: Process completed with exit code 1.