[graphite] Prevents kresd to start if graphite server is not available
kresd fails to start up when the graphite server is not available:
kresd: [system] error while loading config: /usr/lib/knot-resolver/kres_modules/graphite.lua:102: socket:connect: No route to host (workdir '/var/lib/knot-resolver')
This should be a warning, not a critical error preventing start up of kresd.
This is Knot Resolver 5.1.1 running on Debian Buster.