dial: Don't attempt resolve if zeroconf loop isn't running

zeroconf asserts that the loop is running, so if we call this function
without the loop running, it will hit the assert.

Closes home-assistant-libs#641.

pychromecast/dial.py

@@ -35,7 +35,8 @@ def get_host_from_service(service, zconf):
         return service.data + (None,)
 
     try:
-        service_info = zconf.get_service_info("_googlecast._tcp.local.", service.data)
+        if zconf.loop.is_running():
+            service_info = zconf.get_service_info("_googlecast._tcp.local.", service.data)
         if service_info:
             _LOGGER.debug(
                 "get_info_from_service resolved service %s to service_info %s",