Enable layer chaching in gitlab ci.

5 jobs for migration in 30 minutes and 6 seconds (queued for 40 minutes and 29 seconds)
Status Name Job ID Coverage
  Build
passed build #769575

00:10:00

passed buildgui #769576

00:02:46

 
  Test
passed linting #769577

00:03:05

passed tests #769578

00:13:21

80.0%
 
  Release
passed release #769579
manual

00:00:52