Bump postcss from 8.4.27 to 8.4.31

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.27 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@8.4.27...8.4.31)

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

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

package.json

@@ -47,7 +47,7 @@
     "eslint-plugin-import": "^2.27.5",
     "eslint-plugin-storybook": "^0.6.11",
     "eslint-plugin-svelte3": "^4.0.0",
-    "postcss": "^8.4.21",
+    "postcss": "^8.4.31",
     "prettier": "^2.8.0",
     "prettier-plugin-svelte": "^2.8.1",
     "prettier-plugin-tailwindcss": "^0.2.3",