chore(deps-dev): bump postcss from 8.4.19 to 8.4.20

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.19 to 8.4.20.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.19...8.4.20)

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

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

package.json

@@ -42,7 +42,7 @@
     "lerna": "6.1.0",
     "node-notifier": "10.0.1",
     "nx": "15.3.3",
-    "postcss": "8.4.19",
+    "postcss": "8.4.20",
     "regenerator-runtime": "0.13.11",
     "stylelint": "14.16.0",
     "ts-node": "10.9.1",