ci/cd: check cronjob for cache invalidation

[Kamil Samigullin]

See

go-module/.github/workflows/caches.yml

Lines 6 to 8 in 7cc3509

 # TODO:restore replace 14 by 1 after successful testing 
 schedule: 
   - cron: '0 7 14 * *' # https://crontab.guru/#0_7_1_%2A_%2A, CET==UTC+1 

.