fix(package): update next to version 9.3.1

Closes #83

Author: greenkeeper[bot]

package.json

@@ -64,7 +64,7 @@
     "keen-tracking": "^2.0.0",
     "micro": "^9.1.4",
     "micro-route": "^2.4.0",
-    "next": "^5.1.0",
+    "next": "^9.3.1",
     "next-routes": "^1.4.1",
     "prop-types": "^15.6.1",
     "react": "^16.3.1",