TECHNOFAB/nix-gitlab-ci 3.0.1

on GitLab

fix(job): use unmodified job for mkJobRun, otherwise it tries to run "setup_nix_ci" etc. when running locally, which doesn't make sense here

fix(sandbox_helper): fix comparisons, rename TMPDIR variable, add help

1. fixes comparisons with true for flag variables
   
2. renames TMPDIR to NGCI_TMPDIR so it doesn't interfere with the standardized TMPDIR var (and at some point accidentally deleting /tmp)
   
3. add small help message when invalid arg/param is passed
   
4. run git add . on copied git repo in /tmp so staged files stay staged there aswell