[BUG FIX] Fix support of 'pyglet<2.0'. (Genesis-Embodied-AI#1670)

Author: Kashu7100

genesis/vis/visualizer.py

@@ -53,7 +53,7 @@ def __init__(self, scene, show_viewer, vis_options, viewer_options, renderer_opt
             if pyglet.version < "2.0":
                 display = pyglet.canvas.Display()
                 screen = display.get_default_screen()
-                scale = 1.0
+                screen_scale = 1.0
             else:
                 display = pyglet.display.get_display()
                 screen = display.get_default_screen()
@@ -62,7 +62,7 @@ def __init__(self, scene, show_viewer, vis_options, viewer_options, renderer_opt
                 except NotImplementedError:
                     # Probably some headless screen
                     screen_scale = 1.0
-                screen_height, screen_width = screen.height, screen.width
+            screen_height, screen_width = screen.height, screen.width
             self._has_display = True
         except Exception as e:
             if show_viewer: