fix(package): update react to version 16.8.4

Closes #10

Author: greenkeeper[bot]

package.json

@@ -36,7 +36,7 @@
 	"license": "MIT",
 	"dependencies": {
 		"prop-types": "^15.6.2",
-		"react": "16.5.0",
+		"react": "16.8.4",
 		"react-dom": "16.5.0"
 	},
 	"devDependencies": {