client's auth argument is ignored

igwn_alert.client has an argument:

    auth : :class:`Auth <hop.auth.Auth>` (optional)
        A :code:`hop.auth.Auth` object.

However, __init__ completely ignores this, except in the possible edge case where netrc_auth is not None is reached and evaluates to False here.

Assuming we want auth to take precedence over any other arguments (which seems sensible to me), we should change the conditional block to look something like this:

        if noauth:
            auth = False
        else:
            if auth is not None:
                pass
            elif (username and password):
                auth = Auth(username, password)

Here is a simple example that should set up a client using an Auth object, and print True, but instead sets up an unauthenticated session

from hop.auth import Auth
from igwn_alert import client

auth = Auth("test_username", "test_password")
c = client(auth=auth)
print(auth is c.auth_obj)

Output:

/cvmfs/oasis.opensciencegrid.org/ligo/sw/conda/envs/igwn-py39/lib/python3.9/site-packages/igwn_alert/client.py:156: UserWarning: No authentication found. Proceeding with unathenticated session
  warnings.warn("No authentication found. Proceeding "
False