Bump postcss from 8.5.6 to 8.5.12

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.6 to 8.5.12.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.6...8.5.12)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.12
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -37,7 +37,7 @@
     "autoprefixer": "^10.4.21",
     "cross-env": "^7.0.3",
     "hugo-extended": "0.158.0",
-    "postcss": "^8.5.6",
+    "postcss": "^8.5.12",
     "postcss-cli": "^11.0.1",
     "rtlcss": "^4.3.0"
   },