[Web] Fix incorrect Tap offset (#4330)

## Description

Fixes incorrectly calculated `Tap` offset.

## Test plan

This time I don't think it is necessary

Author: m-bert

packages/react-native-gesture-handler/src/web/handlers/TapGestureHandler.ts

@@ -167,7 +167,7 @@ export default class TapGestureHandler extends GestureHandler {
     this.tracker.removeFromTracker(event.pointerId);
 
     this.offsetX += this.lastX - this.startX;
-    this.offsetY += this.lastY = this.startY;
+    this.offsetY += this.lastY - this.startY;
 
     this.updateLastCoords();