Update facerec_on_raspberry_pi.py

Should capture in rgb (not bgr) format.

examples/facerec_on_raspberry_pi.py

@@ -29,7 +29,7 @@ face_encodings = []
 while True:
     print("Capturing image.")
     # Grab a single frame of video from the RPi camera as a numpy array
-    camera.capture(output, format="bgr")
+    camera.capture(output, format="rgb")
 
     # Find all the faces and face encodings in the current frame of video
     face_locations = face_recognition.face_locations(output)