fix(package): set express peerDep at ">=4.0.0" instead of a precise m…

…aj.min.fix

package.json

@@ -28,6 +28,6 @@
     "typescript": "^2.3.2"
   },
   "peerDependencies": {
-    "express": "^4.15.3"
+    "express": ">=4.0.0"
   }
 }