fix(package): update date-fns to version 2.3.0

Closes #407

Author: greenkeeper[bot]

package.json

@@ -6,7 +6,7 @@
     "babel-plugin-styled-components": "^1.10.0",
     "bulma": "^0.7.1",
     "can-use-dom": "^0.1.0",
-    "date-fns": "^1.29.0",
+    "date-fns": "^2.3.0",
     "disqus-react": "^1.0.5",
     "downshift": "^3.0.0",
     "gatsby": "^2.9.4",