Bump postcss from 8.4.38 to 8.4.39

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.38 to 8.4.39.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.38...8.4.39)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -19,7 +19,7 @@
     "astro": "4.11.3",
     "astro-robots-txt": "1.0.0",
     "eslint": "9.5.0",
-    "postcss": "8.4.38",
+    "postcss": "8.4.39",
     "prettier": "3.3.2",
     "prettier-plugin-astro": "0.14.0",
     "prettier-plugin-tailwindcss": "0.6.5",