Update dependency postcss to v8.3.2

Editor assessment

The subject names postcss and the destination version v8.3.2, which fully determines the change. The chore type and deps scope are accurate for a styling-toolchain maintenance bump, and no body is needed for a routine automated update. The Co-authored-by trailer crediting Renovate Bot is well formed, meaningful attribution and the only footer present. Style hygiene is good: imperative phrasing, no trailing period, no ticket junk, moderate subject length, single language. A patch-level bump of this kind requires nothing more of the message, and it communicates everything required in one line without misleading anyone.