Add Gitlab CI config file

8 jobs for master in 25 minutes and 8 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #279890
build

00:03:47

 
  Test
passed #279895
autopkgtest

00:03:16

passed #279896
blhc

00:01:25

passed #279894
lintian

00:02:55

passed #279897
piuparts

00:03:44

passed #279893
reprotest

00:04:00

passed #279892
test-build-all

00:02:35

passed #279891
test-build-any

00:03:21