Skip the rendering test on macOS

macOS is underpowered junk.

kitty_tests/fonts.py

@@ -3,11 +3,13 @@
 # License: GPL v3 Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
 
 from collections import OrderedDict
+import unittest
 
 from kitty.fast_data_types import (
     set_send_sprite_to_gpu, sprite_map_set_layout,
     sprite_map_set_limits, test_render_line, test_sprite_position_for
 )
+from kitty.constants import isosx
 from kitty.fonts.box_drawing import box_chars
 from kitty.fonts.render import render_string, set_font_family
 
@@ -52,6 +54,7 @@ class Rendering(BaseTest):
         test_render_line(line)
         self.assertEqual(len(self.sprites), prerendered + len(box_chars))
 
+    @unittest.skipIf(isosx, 'macOS is too underpowered')
     def test_rendering(self):
         text = 'He\u0347\u0305llo\u0341, w\u0302or\u0306l\u0354d!'
         cells = render_string(text)[-1]