I have installed logwatch and it has begun spamming my /var/log/messages with the following
Nov 13 10:43:01 linux-machine /usr/sbin/cron[30147]: (root) CMD (/usr/sbin/logwatch --service dmeventd)

How can I get it to stop doing this?

I haven't configured logwatch in any way since I installed it. It is configured with Services All as default.