Convert `requests.Timeout` exceptions to `AsanaErrors`

I noticed that we throw exceptions from the requests library without checking if they can be retried.

Traceback (most recent call last):
  ...
 omitted non-relevant info here
  ...
  File "/usr/local/lib/python3.9/dist-packages/asana/page_iterator.py", line 58, in items
    for page in self:
  File "/usr/local/lib/python3.9/dist-packages/asana/page_iterator.py", line 40, in __next__
    result = self.get_initial()
  File "/usr/local/lib/python3.9/dist-packages/asana/page_iterator.py", line 69, in get_initial
    return self.client.get(self.path, self.query, **self.options)
  File "/usr/local/lib/python3.9/dist-packages/asana/client.py", line 171, in get
    return self.request('get', path, params=query, **options)
  File "/usr/local/lib/python3.9/dist-packages/asana/client.py", line 85, in request
    response = getattr(self.session, method)(
  File "/usr/local/lib/python3.9/dist-packages/requests/sessions.py", line 546, in get
    return self.request('GET', url, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/requests_oauthlib/oauth2_session.py", line 521, in request
    return super(OAuth2Session, self).request(
  File "/usr/local/lib/python3.9/dist-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/usr/local/lib/python3.9/dist-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.9/dist-packages/requests/adapters.py", line 529, in send
    raise ReadTimeout(e, request=request)
requests.exceptions.ReadTimeout: HTTPSConnectionPool(host='app.asana.com', port=443): Read timed out. (read timeout=5)

Asana / python-asana

Convert `requests.Timeout` exceptions to `AsanaErrors` #170