Merge pull request adafruit#74 from FoamyGuy/no_bitmap_when_background_none

dont create a background bitmap if background_color is None

Author: tannewt

adafruit_display_text/label.py

@@ -299,7 +299,8 @@ def _update_text(
         self._text = new_text
         self._boundingbox = (left, top, left + right, bottom - top)
 
-        self._update_background_color(self._background_color)
+        if self.background_color is not None:
+            self._update_background_color(self._background_color)
 
     @property
     def bounding_box(self):