chore: Move prop-types to dependencies (#34) (#39)

as recommended in https://www.npmjs.com/package/prop-types#how-to-depend-on-this-package

Author: JalilArfaoui

package-lock.json

@@ -71,8 +71,9 @@
   },
   "peerDependencies": {
     "react": "0.14.x || 15.x || 16.x",
-    "react-dom": "0.14.x || 15.x || 16.x",
-    "prop-types": "15.x"
+    "react-dom": "0.14.x || 15.x || 16.x"
   },
-  "dependencies": {}
+  "dependencies": {
+    "prop-types": "^15.5.7"
+  }
 }