Use Prettier cache (#6165)
Use Prettier cache (#6165)

This commit uses the new `--cache` option since Prettier 2.7.
See https://prettier.io/blog/2022/06/14/2.7.0.html

By default, Prettier saves cache in `node_modules/.cache/prettier`, which has no effect on CI.

Demo on my local machine:

```console
$ time npm run lint:formatting
...
npm run lint:formatting  9.27s user 0.50s system 172% cpu 5.656 total

$ time npm run lint:formatting
...
npm run lint:formatting  1.32s user 0.26s system 125% cpu 1.261 total
```
stylelint/stylelint,stylelint/stylelint,stylelint/stylelint,stylelint/stylelint