build(deps-dev): bump postcss from 7.0.39 to 8.4.31

Bumps [postcss](https://github.com/postcss/postcss) from 7.0.39 to 8.4.31.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@7.0.39...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -42,7 +42,7 @@
     "@testing-library/react": "^11.1.0",
     "@testing-library/user-event": "^12.1.10",
     "autoprefixer": "^9.8.8",
-    "postcss": "^7.0.39",
+    "postcss": "^8.4.31",
     "tailwindcss": "npm:@tailwindcss/postcss7-compat@^2.2.17"
   }
 }