Add proper peer dep

Author: MoOx

package.json

@@ -2,7 +2,7 @@
  "name": "reason-react-navigation",
  "version": "4.0.0-alpha.0",
  "peerDependencies": {
- "react-navigation": "^4.0.0",
+ "@react-navigation/core": "^5.0.0",
  "reason-react": "^0.7.0",
  "reason-react-native": "^0.60.0"
  },