RenovateBot: Update dependency postcss-cli to v11

This MR contains the following updates:

Package	Type	Update	Change
postcss-cli	dependencies	major	^10.0.0 -> ^11.0.0

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Release Notes

postcss/postcss-cli (postcss-cli)

v11.0.0

Compare Source

• BREAKING: Require Node.js v18+ (#​464)
• Upgrade to postcss-load-config@5 for improved ESM & TS config support (#​461, #​462)

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