make images smaller

Signed-off-by: Adrian C. Hinrichs <adrian.hinrichs@rwth-aachen.de>
4 jobs for dev in 10 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
failed #356649
build testing

00:00:10

failed #356648
build testing

00:00:07

failed #352735
build testing

00:00:06

 
  Deploy
skipped #352736
deploy
 
Name Stage Failure
failed
build testing Build
 * [new tag]         v2.0           -> v2.0
* [new tag] v2.2 -> v2.2
* [new tag] v2.2.1 -> v2.2.1
Checking out df9fa9b1 as dev...

Skipping Git submodules setup
$ echo "$CI_JOB_TOKEN" | docker login registry.git.rwth-aachen.de --username gitlab-ci-token --password-stdin
error during connect: Post http://docker:2375/v1.39/auth: dial tcp: lookup docker on 10.96.0.10:53: no such host
ERROR: Job failed: command terminated with exit code 1