gitlab-ci.yml: Pin dind to a specific version

As advised by https://gitlab.com/gitlab-org/gitlab-runner/issues/4566
2 jobs for master in 23 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed #300718
build

00:00:23

failed #300368
build

00:00:21

 
Name Stage Failure
failed
build Build
Skipping Git submodules setup
$ docker info
errors pretty printing info
Client:
Debug Mode: false

Server:
ERROR: Cannot connect to the Docker daemon at tcp://docker:2375/. Is the docker daemon running?
ERROR: Job failed: exit code 1