removed git installation. this is a gitlab-runner issue.

Status Job ID Name Coverage
  Test
failed #15993
nix.test

00:00:03

passed #15991
nix.test

00:00:08

 
Name Stage Failure
failed
nix.test Test
Using Shell executor...
Running on argo-phi1.mcs.anl.gov...
Cloning repository...
Cloning into '/home/gitlab-runner/builds/259091ff/0/argo/argotest'...
Checking out 4946d759 as master...
Skipping Git submodules setup
$ ./tests.hs
/usr/bin/env: nix-shell: No such file or directory
ERROR: Job failed: exit status 1