remove User#locale (#4932)

src/structures/User.js

@@ -28,7 +28,6 @@ class User extends Base {
     this.id = data.id;
 
     this.system = null;
-    this.locale = null;
     this.flags = null;
 
     this._patch(data);
@@ -81,14 +80,6 @@ class User extends Base {
       this.system = Boolean(data.system);
     }
 
-    if ('locale' in data) {
-      /**
-       * The locale of the user's client (ISO 639-1)
-       * @type {?string}
-       */
-      this.locale = data.locale;
-    }
-
     if ('public_flags' in data) {
       /**
        * The flags for this user