add telegraf user to docker group for docker stats

1 job from master in 13 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #10321
test

00:00:13

 
Name Stage Failure
failed
test Test
  on bsl3-git-builder-prod-1.bsl3.beryju.org 57cf9187
Using Docker executor with image ruby:2.3 ...
Pulling docker image ruby:2.3 ...
Using docker image sha256:508b5d014b67cc6e020ceaeb2983a413dd87ce962e3ee2c6fadcb17aa68d3a6f for ruby:2.3 ...
Running on runner-57cf9187-project-101-concurrent-0 via 4207824e962c...
Cloning repository...
Cloning into '/builds/beryjuorg-puppet/beryjuorg-gitlab'...
fatal: unable to access 'https://gitlab-ci-token:xxxxxxxxxxxxxxxxxxxx@git.beryju.org/beryjuorg-puppet/beryjuorg-gitlab.git/': Could not resolve host: git.beryju.org
ERROR: Job failed: exit code 1