chore(deps): bump postcss and @openedx/paragon

Bumps [postcss](https://github.com/postcss/postcss) to 8.5.6 and updates ancestor dependency [@openedx/paragon](https://github.com/openedx/paragon). These dependencies need to be updated together.


Updates `postcss` from 7.0.39 to 8.5.6
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/7.0.39...8.5.6)

Updates `@openedx/paragon` from 23.19.1 to 23.19.1
- [Release notes](https://github.com/openedx/paragon/releases)
- [Changelog](https://github.com/openedx/paragon/blob/release-23.x/CHANGELOG.md)
- [Commits](https://github.com/openedx/paragon/compare/v23.19.1...v23.19.1)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.6
  dependency-type: indirect
- dependency-name: "@openedx/paragon"
  dependency-version: 23.19.1
  dependency-type: direct:production
...

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

package.json

@@ -45,7 +45,7 @@
     "@fortawesome/free-solid-svg-icons": "5.15.4",
     "@fortawesome/react-fontawesome": "^0.1.4",
     "@openedx/frontend-plugin-framework": "^1.7.0",
-    "@openedx/paragon": "^23.4.5",
+    "@openedx/paragon": "^23.19.1",
     "@popperjs/core": "2.11.8",
     "@reduxjs/toolkit": "1.9.7",
     "buffer": "^6.0.3",