Update epd2in13_V2.py

This will allow the screen to be cleared without the color parameter being explicitly included (similar to the 2in7 library)

RaspberryPi_JetsonNano/python/lib/waveshare_epd/epd2in13_V2.py

@@ -280,7 +280,7 @@ class EPD:
         self.send_data2(image)  
         self.TurnOnDisplay()
     
-    def Clear(self, color):
+    def Clear(self, color=0xFF):
         if self.width%8 == 0:
             linewidth = int(self.width/8)
         else: