Add Gitlab CI config file

8 jobs for master in 22 minutes and 39 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Build
passed #279818
build

00:03:24

 
  Test
passed #279823
autopkgtest

00:04:31

passed #279824
blhc

00:01:20

passed #279822
lintian

00:01:49

passed #279825
piuparts

00:03:19

passed #279821
reprotest

00:02:39

passed #279820
test-build-all

00:02:16

passed #279819
test-build-any

00:03:17