`prettier` `pre-commit` hook doesn't work with the latest version of `nodeenv` on Windows

[alexdewar]

See CI failures here: #20

The upstream repo for the hook has been archived since April, without explanation: https://github.com/pre-commit/mirrors-prettier

Possible replacements:

• https://github.com/pre-commit/pre-commit-hooks
• https://github.com/macisamuele/language-formatters-pre-commit-hooks

[alexdewar]

This particular issue seemed to fix itself but we still need to move away from the prettier hook. See #52.