build(deps-dev): bump autoprefixer in /csfieldguide

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 10.4.19 to 10.4.20.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@10.4.19...10.4.20)

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

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

csfieldguide/package.json

@@ -7,7 +7,7 @@
         "@babel/core": "^7.25.2",
         "@babel/preset-env": "^7.25.3",
         "ansi-colors": "4.1.3",
-        "autoprefixer": "10.4.19",
+        "autoprefixer": "10.4.20",
         "babelify": "^10.0.0",
         "bootstrap": "4.6.2",
         "browser-sync": "3.0.2",