fix(deps): update dependency polished to v4

Author: renovate-bot

package.json

@@ -26,7 +26,7 @@
     "gatsby-source-filesystem": "^2.3.32",
     "lodash": "^4.17.20",
     "mdx-utils": "^0.2.0",
-    "polished": "^3.6.7",
+    "polished": "^4.0.2",
     "prism-react-renderer": "^1.1.1",
     "prop-types": "^15.7.2",
     "react": "^16.13.1",

yarn.lock

@@ -12438,10 +12438,10 @@ pnp-webpack-plugin@^1.6.4:
   dependencies:
     ts-pnp "^1.1.6"
 
-polished@^3.6.7:
-  version "3.6.7"
-  resolved "https://registry.yarnpkg.com/polished/-/polished-3.6.7.tgz#44cbd0047f3187d83db0c479ef0c7d5583af5fb6"
-  integrity sha512-b4OViUOihwV0icb9PHmWbR+vPqaSzSAEbgLskvb7ANPATVXGiYv/TQFHQo65S53WU9i5EQ1I03YDOJW7K0bmYg==
+polished@^4.0.2:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/polished/-/polished-4.0.2.tgz#58f6a215dd93038c5b3808725ed31e208c2e6403"
+  integrity sha512-TJd61zfqQrVdysU04GzSKThFWgQrpFLrHZgKfv5BwRSxOrqFIgzLYKWWML4Q8EMMsJBUgwMitI10w9lpBMo+xQ==
   dependencies:
     "@babel/runtime" "^7.9.2"