Update .gitlab-ci.yml, Dockerfile files

1 job for ci in 29 seconds
Status Job ID Name Coverage
  Build
failed #159441
build

00:00:29

 
Name Stage Failure
failed
build Build
#9 exporting manifest list sha256:00ca5c0b09b79bc2222c5b3c15500f7344d715ffc4dcd81fe2532906bd9dffdb
#9 exporting manifest list sha256:00ca5c0b09b79bc2222c5b3c15500f7344d715ffc4dcd81fe2532906bd9dffdb 0.2s done
#9 pushing layers
#9 pushing layers 0.4s done
#9 pushing manifest for omi-registry.e-technik.uni-ulm.de/sv/buildx-demo:latest 0.1s done
#9 DONE 2.2s
$ docker tag "$CI_REGISTRY_IMAGE" "$CI_REGISTRY_IMAGE":"$CI_COMMIT_REF_NAME"
Error response from daemon: No such image: omi-registry.e-technik.uni-ulm.de/sv/buildx-demo:latest
ERROR: Job failed: exit code 1