Add resiliance to timeouts when trying to fetch remote resources

[Lyalpha]

The default timeout for astropy's download_file is only 10 seconds. Seemingly the servers can be overloaded now in O4 as everyone tries to do the same thing and if this times out the sentinel fails to process a notice and does not retry.

Increasing timeout is probably needed at a minimum, but some retry logic with a backoff would also be useful.