Pass linting checks

[ErikSchierboom]

The configlet tool has a lint command that checks if a track's configuration files are properly structured - both syntactically and semantically. Misconfigured tracks may not sync correctly, may look wrong on the website, or may present a suboptimal user experience, so configlet's guards play an important part in maintaining the integrity of Exercism.

We've updated configlet to work with v3 tracks, which have a different set of requirements than v2 tracks.

The full list of rules that are checked by the linter can be found in this spec.

Tracks must make sure they pass all the (v3 track) checks defined in configlet lint.