[enh] add .gitlab-ci.yml

4 jobs for gitlab-ci in 15 minutes and 37 seconds (queued for 6 seconds)
Status Name Job ID Coverage
  Checks
passed build #60130

00:00:17

passed checks #60131

00:06:33

 
  Tests
passed tests #60132

00:04:02

 
  Release
passed ubuntu-18.04 #60133
manual

00:05:01