Use triple equals for dates

Not sure what would need to be coerced here, triple equals might help ensure a more accurate diff. 


```js
  const date1 = new Date(Date.UTC(96, 1, 2, 3, 4, 5));

  console.log(date1.valueOf());
  // expected output: 823230245000

  const date2 = new Date("02 Feb 1996 03:04:05 GMT");

  console.log(date2.valueOf());
  // expected output: 823230245000

  console.log(date1.valueOf() === date2.valueOf());
  // expected output: true
```

Author: JamesGelok

src/diff/index.js

@@ -13,7 +13,7 @@ const diff = (lhs, rhs) => {
   }, {});
 
   if (isDate(l) || isDate(r)) {
-    if (l.valueOf() == r.valueOf()) return {};
+    if (l.valueOf() === r.valueOf()) return {};
     return r;
   }