chore(deps): update dependency postcss-cli to v6

This MR contains the following updates:

Package	Type	Update	Change	References
postcss-cli	devDependencies	major	^2.5.2 -> ^6.0.0	source

---

Renovate configuration

📅 Schedule: At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever MR becomes conflicted.

🔕 Ignore: Close this MR and you won't be reminded about this update again.

---

This MR has been generated by Renovate Bot.