Bump postcss from 8.4.21 to 8.4.22

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.21 to 8.4.22.
- [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/8.4.21...8.4.22)

---
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

@@ -28,7 +28,7 @@
     "eslint-config-standard-with-typescript": "^34.0.1",
     "eslint-plugin-svelte3": "^4.0.0",
     "flourite": "^1.2.3",
-    "postcss": "^8.4.21",
+    "postcss": "^8.4.22",
     "sass": "^1.61.0",
     "svelte": "^3.58.0",
     "svelte-check": "^3.2.0",