fix(package): update downshift to version 5.0.5

Closes #416

Author: greenkeeper[bot]

package.json

@@ -8,7 +8,7 @@
     "can-use-dom": "^0.1.0",
     "date-fns": "^1.29.0",
     "disqus-react": "^1.0.5",
-    "downshift": "^3.0.0",
+    "downshift": "^5.0.5",
     "gatsby": "^2.9.4",
     "gatsby-image": "^2.0.20",
     "gatsby-plugin-algolia": "^0.3.0",