Update dependency postcss-loader to v6 (#41460)
Update dependency postcss-loader to v6 (#41460)

* Update dependency postcss-loader to v6

* Revert "Update dependency postcss-loader to v6"

This reverts commit c3d59a824120ab01be470230bce8aebe9112178b.

* Do not upgrade postcss-loader until webpack 5

Co-authored-by: Renovate Bot <c71e7261d37a4f6ae4cfb0cbd79081310a237e67@renovateapp.com>
Co-authored-by: Zoltán Bedi <af1a6e936c8cd291cb5642b11ffc035fda242389@gmail.com>
grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana,grafana/grafana