Update DNS plug-in on network change

Restart the DNS plug-in on network change. This makes sure any
potential host OS DNS configuration changes get picked up by the DNS
plug-in as well.

supervisor/host/network.py

@@ -173,6 +173,9 @@ async def update(self, *, force_connectivity_check: bool = False):
                 "No network D-Bus connection available", _LOGGER.error
             ) from err
 
+        # This potentially updated the DNS configuration. Make sure the DNS plug-in
+        # picks up the latest settings.
+        await self.sys_plugins.dns.restart()
         await self.check_connectivity(force=force_connectivity_check)
 
     async def apply_changes(