Update darknet.py

# Example code

import os
import sys

os.environ['DARKNET_PATH'] = '/usr/local/darknet'
sys.path.append(os.environ['DARKNET_PATH'])

import darknet


def main():
    network, class_names, class_colors = darknet.load_network(
        '../nscan-train/data/cfg/yolov4-tiny-3l-numbers-12.cfg',
        '../nscan-train/data/numbers.data',
        './data/weights/numbers/yolov4-tiny-3l-numbers-12_last.weights',
        batch_size=1
    )


if __name__ == '__main__':
    main()