Bump cssnano from 4.1.11 to 5.0.0

Bumps [cssnano](https://github.com/cssnano/cssnano) from 4.1.11 to 5.0.0.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/v4.1.11...cssnano@5.0.0)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -49,7 +49,7 @@
         "babelify": "^10.0.0",
         "browserify": "^17.0.0",
         "cross-env": "^7.0.3",
-        "cssnano": "^4.1.11",
+        "cssnano": "^5.0.0",
         "del": "^6.0.0",
         "factor-bundle": "^2.5.0",
         "gulp": "^4.0.2",