Update dependency postcss to v8.5.23

[renovate]

This PR contains the following updates:

Package	Change	Age	Confidence
postcss (source)	8.5.18 → 8.5.23

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Release Notes

postcss/postcss (postcss)

v8.5.23

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• Do not load source map without opts.from for security reasons.

v8.5.22

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• Fixed custom property losing semicolon before a comment (by @​sarathfrancis90).

v8.5.21

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• Fixed childless at-rule losing semicolon before comment (by @​sarathfrancis90).
• Fixed docs (by @​isker).

v8.5.20

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• Fixed missing space if AtRule#params is set after (by @​sarathfrancis90).
• Fixed mixing AST error on warnings (by @​MahinAnowar).

v8.5.19

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• Fixed cleaning before for new nodes inserted to Root (by @​MahinAnowar).

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