我在虚拟环境中运行 Python，并且在其中执行以下操作：
python -V
返回：
Python 3.9.5
然后我运行：
pip install opencv-contrib-python
并得到：
DEPRECATION: Python 3.5 reached the end of its life on September 13th, 2020. Please upgrade your Python as Python 3.5 is no longer maintained. pip 21.0 will drop support for Python 3.5 in January 2021. pip 21.0 will remove support for this functionality.
ERROR: Could not find a version that satisfies the requirement opencv-contrib-python
ERROR: No matching distribution found for opencv-contrib-python
如果我已经在最新的 Python 上，我需要运行哪些命令才能安装 opencv？