Replace cosmiconfig with lilconfig (#6038)

* Replace cosmiconfig with lilconfig

It's already replaced in postcss-load-config

See https://github.com/postcss/postcss-load-config/blob/main/package.json#L26

* Manually restore parse-json in lockfile removed by npm conflict resolver

* Revert `postcss` version change

Co-authored-by: Brad Cornes <[email protected]>

Author: TrySound