Improve request timeout handling

[RatJuggler]

Catch timeouts and handle gracefully so we don't get this in the log file.

Traceback (most recent call last):
File "/usr/local/bin/syncgandidns", line 10, in
sys.exit(syncgandidns())
File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 829, in call
return self.main(*args, **kwargs)
File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 782, in main
rv = self.invoke(ctx)
File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 1066, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/local/lib/python3.7/dist-packages/click/core.py", line 610, in invoke
return callback(*args, **kwargs)
File "/usr/local/lib/python3.7/dist-packages/syncgandidns/main.py", line 73, in syncgandidns
do_sync(domains, apikey, no_ipv4, ipv4, no_ipv6, ipv6)
File "/usr/local/lib/python3.7/dist-packages/syncgandidns/sync_ip_address.py", line 51, in do_sync
_sync_ip(domain, 'IPV6', update_ipv6, gandi_api.get_ipv6_address, gandi_api.update_ipv6_address)
File "/usr/local/lib/python3.7/dist-packages/syncgandidns/sync_ip_address.py", line 11, in _sync_ip
current_ip = get_ip(domain)
File "/usr/local/lib/python3.7/dist-packages/syncgandidns/gandi_api.py", line 55, in get_ipv6_address
return self._get_domain_record_resource_value(domain, 'AAAA')
File "/usr/local/lib/python3.7/dist-packages/syncgandidns/gandi_api.py", line 30, in _get_domain_record_resource_value
timeout=4)
File "/usr/local/lib/python3.7/dist-packages/requests/api.py", line 76, in get
return request('get', url, params=params, **kwargs)
File "/usr/local/lib/python3.7/dist-packages/requests/api.py", line 61, in request
return session.request(method=method, url=url, **kwargs)
File "/usr/local/lib/python3.7/dist-packages/requests/sessions.py", line 542, in request
resp = self.send(prep, **send_kwargs)
File "/usr/local/lib/python3.7/dist-packages/requests/sessions.py", line 655, in send
r = adapter.send(request, **kwargs)
File "/usr/local/lib/python3.7/dist-packages/requests/adapters.py", line 529, in send
raise ReadTimeout(e, request=request)
requests.exceptions.ReadTimeout: HTTPSConnectionPool(host='api.gandi.net', port=443): Read timed out. (read timeout=4)