fixed data type check

ar_tag_pose/board_pose.py

@@ -26,7 +26,7 @@ class BoardPose(abc.ABC):
 		self.src_images = None
 		if source.isnumeric():
 			self.device_id = int(source)
-		elif isinstance(source, str):
+		else:
 			mime_type = mimetypes.guess_type(source)[0]
 			if "video" in mime_type:
 				self.src_video = source