⬆️ Update dependency cssnano to v5

Author: renovate-bot

package.json

@@ -55,7 +55,7 @@
     "@rollup/plugin-replace": "^2.3.4",
     "@sindresorhus/slugify": "^1.1.0",
     "chalk": "^4.1.0",
-    "cssnano": "^4.1.10",
+    "cssnano": "^5.0.0",
     "del": "^6.0.0",
     "figures": "^3.2.0",
     "joycon": "^2.2.5",