Undo change of default to pixel

Author: Jason Symons

adafruit_is31fl3741/__init__.py

@@ -308,7 +308,7 @@ def fill(self, color: int = 0) -> None:
                 self[addrs[self.g_offset]] = green
                 self[addrs[self.b_offset]] = blue
 
-    def pixel(self, x: int, y: int, color: int = 0) -> Union[int, None]:
+    def pixel(self, x: int, y: int, color: Optional[int] = None) -> Union[int, None]:
         """
         Set or retrieve RGB color of pixel at position (X,Y).