touch all test files to allow students to update to Stack 18.14, or convince ourselves that this is unnecessary

[petertseng]

In https://github.com/exercism/haskell/pull/1012 we updated to Stack 18.14. Students who start exercises that had not been started before will get 18.14 in their stack.yaml if they download via CLI (tested and confirmed).

In contrast, I tried downloading an exercise that I had in progress before https://github.com/exercism/haskell/pull/1012 was merged, and its stack.yaml still said stack 16.21. stack.yaml is not one of the important files listed in https://github.com/exercism/website/blob/c861c76b1aaff97a719e3dfb94884b65f2744017/app/models/git/exercise.rb#L185 that is used to determine whether a student needs to update their files. So, every test file might need to be updated to allow students to get stack-18.14. Note right now that there is a sha1 hash at the bottom of each. You may either update this sha1 hash with a new value, remove it completely, or replace it with a string like "stack lts-18.14". I have no preference between the three options.

Alternatively, I may have misunderstood the situation (for debugging purposes, the exercises in question were gigasecond which is deprecated and nucleotide-count which isn't), and we can do something else to allow students to get the new files. Or alternatively, we may decide it's fine if students don't get LTS 18.14 and don't need to do this.

[petertseng]

Check files.invalidator field in https://github.com/exercism/configlet/releases/tag/4.0.0-beta.2 ?

[ErikSchierboom]

@petertseng The files.invalidator field should indeed help solve this issue.