build: update cssnano (#1730)

Author: Kikobeats

package.json

@@ -114,8 +114,8 @@
     "@vercel/analytics": "~1.3.1",
     "babel-plugin-styled-components": "~2.1.4",
     "beauty-error": "~1.2.18",
-    "cssnano": "~6.0.2",
-    "cssnano-preset-advanced": "~6.0.2",
+    "cssnano": "~7.0.4",
+    "cssnano-preset-advanced": "~7.0.4",
     "dlv": "~1.1.3",
     "gatsby": "~5.13.7",
     "gatsby-plugin-advanced-sitemap": "~2.1.0",