[test] fix for gitlab image

2 jobs for dev-test in 5 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
failed #1540
build

00:00:05

failed #1538
build

00:00:04

 
Name Stage Failure
failed
build Build There has been a runner system failure, please try again
Running with gitlab-runner 13.12.0 (7a6612da)
on gitlab.iscpif.fr 1paGa5-x
Preparing the "docker" executor
Using Docker executor with image fpco/stack-build:lts-16.26-garg ...
Pulling docker image fpco/stack-build:lts-16.26-garg ...
WARNING: Failed to pull image with policy "always": Error response from daemon: manifest for fpco/stack-build:lts-16.26-garg not found: manifest unknown: manifest unknown (manager.go:205:1s)
ERROR: Job failed (system failure): failed to pull image "fpco/stack-build:lts-16.26-garg" with specified policies [always]: Error response from daemon: manifest for fpco/stack-build:lts-16.26-garg not found: manifest unknown: manifest unknown (manager.go:205:1s)