fix(redux/functions): fix typo

The intention of the code is (1) to return target if none of the setters lead
to an actual change, (2) to not modify target, and (3) to do it with a 1
copyOnWrite at most.

react/features/base/redux/functions.js

     let t = target;
 
     for (const property in source) { // eslint-disable-line guard-for-in
-        t = set(t, property, source[property], t === target);
+        t = _set(t, property, source[property], t === target);
     }
 
     return t;