update peerDeps to react 16.6.0

package.json

@@ -137,7 +137,7 @@
     "shortid": "^2.2.14"
   },
   "peerDependencies": {
-    "react": ">= ^16.3.0",
+    "react": ">= ^16.6.0",
     "styled-components": ">= ^3.2.3 || >= ^4.0.0"
   }
 }