build(deps-dev): bump cssnano from 7.0.5 to 7.0.6 (#406)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.0.5 to 7.0.6.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.0.5...cssnano@7.0.6)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -12,7 +12,7 @@
     "@types/webextension-polyfill": "^0.10.7",
     "@typescript-eslint/eslint-plugin": "^7.16.1",
     "autoprefixer": "^10.4.20",
-    "cssnano": "^7.0.5",
+    "cssnano": "^7.0.6",
     "del": "^7.1.0",
     "eslint": "^8.57.0",
     "gulp": "^5.0.0",