完整的报错信息：
ERROR: Could not find a version that satisfies the requirement cv2 (from versions: none) ERROR: No matching distribution found for cv2
方法：
pip install opencv-python
完整的报错信息：
ERROR: Could not find a version that satisfies the requirement cv2 (from versions: none) ERROR: No matching distribution found for cv2
方法：
pip install opencv-python