Fix stack tests

[mgajda]

This occurs on GitLab CI:

Test suite failure for package json-autotype-3.0.1
    json-autotype-examples:  exited with: ExitFailure 1
Full log available at /builds/migamake/json-autotype/.stack-work/logs/json-autotype-3.0.1-test.log


    stack: WARNING! Expecting stack options comment at line 1, column 1
    stack: WARNING! Missing or unusable stack options specification
    stack: WARNING! Using runghc without any additional stack options
    Invalid argument `run'
    Error executing interpreter command: stack run -- runghc -- examples/union.json --outputFilename output/Union.hs
    
    Usage: stack [--help] [--version] [--numeric-version] [--hpack-numeric-version]
                 [--docker*] [--nix*] ([--verbosity VERBOSITY] | [-v|--verbose] |
                 [--silent]) [--[no-]time-in-log] [--stack-root STACK-ROOT]
                 [--work-dir WORK-DIR] [--[no-]system-ghc] [--[no-]install-ghc]
                 [--arch ARCH] [--ghc-variant VARIANT] [--ghc-build BUILD]
                 [-j|--jobs JOBS] [--extra-include-dirs DIR] [--extra-lib-dirs DIR]
                 [--with-gcc PATH-TO-GCC] [--with-hpack HPACK]
                 [--[no-]skip-ghc-check] [--[no-]skip-msys] [--local-bin-path DIR]
                 [--[no-]modify-code-page] [--[no-]allow-different-user]
                 [--[no-]dump-logs] [--resolver RESOLVER] [--compiler COMPILER]
                 [--[no-]terminal] [--color WHEN] [--terminal-width INT]
                 [--stack-yaml STACK-YAML] COMMAND|FILE
    Running json-autotype with executable "stack" and arguments ["run","--"]
    json-autotype-examples: user error (test case "examples/union.json" failed with ExitFailure 1)

[workshub]

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[mgajda]

This should be tackled as part of #22

[workshub]

@nikhiljahagirdar started working on this issue via WorksHub.

[workshub]

@mazeboard started working on this issue via WorksHub.