chore(deps-dev): bump autoprefixer from 10.4.20 to 10.4.21 (#1119)

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 10.4.20 to 10.4.21.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@10.4.20...10.4.21)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -71,7 +71,7 @@
     "@pattern-lab/engine-handlebars": "^6.1.0",
     "@pattern-lab/starterkit-handlebars-demo": "^6.1.0",
     "@pattern-lab/uikit-workshop": "^6.1.0",
-    "autoprefixer": "^10.4.20",
+    "autoprefixer": "^10.4.21",
     "backstopjs": "^6.3.25",
     "cpr": "^3.0.1",
     "cssnano": "^7.0.6",