Bump autoprefixer from 10.4.19 to 10.4.20 in /plumage

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:production
  update-type: version-update:semver-patch
...

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

plumage/package.json

@@ -2,7 +2,7 @@
   "name": "plumage-webassets-pipeline",
   "description": "Plumage dependencies for the webassets compilation pipeline.",
   "dependencies": {
-    "autoprefixer": "^10.4.19",
+    "autoprefixer": "^10.4.20",
     "bootstrap": "^5.3.3",
     "postcss": "^8.4.47",
     "postcss-cli": "^11.0.0"