build(deps): bump postcss from 8.4.6 to 8.4.12 in /docs (golangci#2731)

Author: dependabot[bot]

docs/package-lock.json

@@ -37,7 +37,7 @@
     "gatsby-transformer-sharp": "^4.11.0",
     "gatsby-transformer-yaml": "^4.11.0",
     "polished": "^4.1.4",
-    "postcss": "^8.4.6",
+    "postcss": "^8.4.12",
     "prism-react-renderer": "^1.3.1",
     "prop-types": "^15.8.1",
     "puppeteer": "^13.1.3",