Change Unit representaiton from {} to undefined (#267)

* Change Unit representaiton from `{}` to `undefined`

* Update changelog

Author: JordanMartinez

CHANGELOG.md

@@ -11,6 +11,7 @@ New features:
 Bugfixes:
 
 Other improvements:
+- Changed `unit`'s FFI representation from `{}` to `undefined` (#267 by @JordanMartinez)
 
 ## [v5.0.1](https://github.com/purescript/purescript-prelude/releases/tag/v5.0.1) - 2021-05-11
 

src/Data/Unit.js

@@ -1,3 +1,3 @@
 "use strict";
 
-exports.unit = {};
+exports.unit = undefined;