build(deps-dev): bump cssnano from 6.0.3 to 6.0.4

Bumps [cssnano](https://github.com/cssnano/cssnano) from 6.0.3 to 6.0.4.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/[email protected]@6.0.4)

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

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

Author: dependabot[bot]

package-lock.json

@@ -74,7 +74,7 @@
     "autoprefixer": "^10.4.17",
     "backstopjs": "^6.3.12",
     "cpr": "^3.0.1",
-    "cssnano": "^6.0.3",
+    "cssnano": "^6.0.4",
     "details-element-polyfill": "^2.4.0",
     "dialog-polyfill": "^0.5.6",
     "dotenv": "^16.4.5",