Update package.json

correct postinstall

Author: monkeywithacupcake

package.json

@@ -19,10 +19,10 @@
     "lerna": "^3.1.2"
   },
   "dependencies": {
-    "opencollective": "^1.0.3"
+    "opencollective-postinstall": "^2.0.0",
   },
   "collective": {
     "type": "opencollective",
     "url": "https://opencollective.com/typescript-webpack-starter"
   }
-}
+}