Correct use of sx and sy

Correcting a typo I made just previously.

Author: vanicat

arcade/tilemap/tilemap.py

@@ -924,8 +924,8 @@ def _process_object_layer(
                         - cur_object.coordinates.y
                     ) * scaling + offset[1]
 
-                    ex = x + cur_object.size.width * scaling
-                    ey = y - cur_object.size.height * scaling
+                    ex = sx + cur_object.size.width * scaling
+                    ey = sy - cur_object.size.height * scaling
 
                     p1 = [sx, sy]
                     p2 = [ex, sy]