chore(deps-dev): bump postcss from 8.5.19 to 8.5.20 (#100)

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.19 to 8.5.20.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.19...8.5.20)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.18
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -58,7 +58,7 @@
     "jsdom": "^28.1.0",
     "pixelmatch": "^7.2.0",
     "pngjs": "^7.0.0",
-    "postcss": "^8.5.19",
+    "postcss": "^8.5.20",
     "prettier": "^3.9.5",
     "tailwindcss": "^4.1.8",
     "typescript": "5.9.3",