【Python】解决pip安装时dependency conflict

用pip install xxx安装库时有时候会遇到下面提示：

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

可以用下面命令安装试试：

python3 -m pip install xxx 

有可能解决该问题。