Minor: removed extra semicolon (#937)

Summary:
X-link: https://github.com/facebook/litho/pull/937

Latest `emscripten` compiler shows the next warning:
```
yoga/event/event.h:83:6: warning: extra ‘;’ [-Wpedantic]
   83 |     };
      |      ^
```

This small PR fixes it

Pull Request resolved: https://github.com/facebook/yoga/pull/1240

Test Plan: landcastle

Reviewed By: cortinico, mdvacca

Differential Revision: D44775620

Pulled By: philIip

fbshipit-source-id: 79b7ca5df2a31ac9a6ef24ef55d4acb6117a8acb

yoga/event/event.h

@@ -80,7 +80,7 @@ struct YOGA_EXPORT Event {
     template <Type E>
     const TypedData<E>& get() const {
       return *static_cast<const TypedData<E>*>(data_);
-    };
+    }
   };
 
   static void reset();