fix(package): update react-navigation to version 4.0.4

Closes #219

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "react-native-render-html": "^4.1.2",
     "react-native-styled-text": "^1.0.1",
     "react-native-swiper": "^1.5.14",
-    "react-navigation": "^3.11.0",
+    "react-navigation": "^4.0.4",
     "react-navigation-backhandler": "^1.3.2",
     "react-switch": "^5.0.0",
     "react-transition-group": "^4.1.1",