Use taplo to format toml files

[FirelightFlagboy]

taplo is a tool used to format toml files.

It's included in the vscode extension tamasfe.even-better-toml

Currently it doesn't have a pre-commit hook, but that worked on tamasfe/taplo#535

But following the promising PR tamasfe/taplo#549

we could use the hook:

  - repo: https://github.com/redeboer/taplo-pre-commit
    rev: v0.9.1rc1
    hooks:
      - id: taplo