Bump postcss from 5.2.18 to 8.4.31

Bumps [postcss](https://github.com/postcss/postcss) from 5.2.18 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/commits/8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:production
...

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

Author: dependabot[bot]

package-lock.json

@@ -32,7 +32,7 @@
   "dependencies": {
     "caniuse-api": "^3.0.0",
     "parse-css-font": "^2.0.2",
-    "postcss": "^5.0.16",
+    "postcss": "^8.4.31",
     "quote": "^0.4.0"
   },
   "devDependencies": {