Add gitlab-ci

1 job for master in 34 seconds (queued for 18 seconds)
Name Stage Failure
build Test
Checking out 97e35cb3 as master...

Skipping Git submodules setup
Executing "step_script" stage of the job script
$ stack build
No compiler found, expected minor version match with ghc-8.10.4 (x86_64-tinfo6) (based on resolver setting in /builds/philipp.middendorf/graphviz-sql-hs/stack.yaml).
To install the correct GHC into /root/.stack/programs/x86_64-linux/, try running "stack setup" or use the "--install-ghc" flag. To use your system GHC installation, run "stack config set system-ghc --global true", or use the "--system-ghc" flag.
Cleaning up file based variables
ERROR: Job failed: command terminated with exit code 1