fix path in cron.sh for nextcloud image #82

Job	Run time
Build App Containers (minecraft) / Build minecraft	27s
Build App Containers (indico) / Build indico	2m 35s
Build App Containers (etherpad) / Build etherpad	44s
Build App Containers (limesurvey) / Build limesurvey	32s
Build App Containers (nextcloud) / Build nextcloud	1m 29s
Build App Containers (sogo) / Build sogo	2m 41s
	8m 28s

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