Merge branch 'fix_ci' into 'dev'

fix gitlab ci by setting docker versions

See merge request bmp-caosdb/caosdb-server!12

.gitlab-ci.yml

@@ -24,14 +24,12 @@
 
 variables:
   CI_REGISTRY_IMAGE: $CI_REGISTRY/caosdb-server-testenv:latest
-  # With dind the docker deamon is available on the network
-  DOCKER_HOST: tcp://docker:2375/
   # When using dind, it's wise to use the overlayfs driver for
   # improved performance.
   DOCKER_DRIVER: overlay2
 
 services:
-  - docker:dind
+  - docker:19.03-dind
 
 image: $CI_REGISTRY_IMAGE
 stages:
@@ -66,7 +64,7 @@ trigger_build:
 # Build a docker image in which tests for this repository can run
 build-testenv:
   tags: [ docker ]
-  image: docker:latest
+  image: docker:19.03
   stage: setup
   script:
     - cd src/test/docker