Try imports in separate blocks

As @FoamyGuy pointed out, you may have one or the other library, both or none.
This handles the combinations properly.

Author: rsbohn

adafruit_displayio_layout/widgets/cartesian.py

@@ -33,6 +33,10 @@
 
 try:
     import bitmaptools
+except ImportError:
+    pass
+
+try:
     from typing import Tuple
 except ImportError:
     pass