Update HTML channel logs every 15 minutes

Correct the cronjob for the log prettifier to run every 15 minutes
instead of on the 15th minute.

Change-Id: Id738a5d793e22f4253461e0bf45bb222fd2a31ab

playbooks/roles/limnoria/tasks/main.yaml

@@ -57,7 +57,7 @@
     name: 'opendev {{ item.key }} logs2html'
     state: present
     user: root
-    minute: 15
+    minute: '*/15'
     job: >-
         /usr/local/bin/docker-compose -f /etc/ircbot-docker/docker-compose.yaml exec -T ircbot
         bash -c "find /var/lib/limnoria/opendev/logs/ChannelLogger/{{ item.key }}/ -mindepth 1 -maxdepth 1 -type d | xargs -n1 logs2html"