我尝试将pandas-datareader软件包安装到Anaconda中，但它不起作用。
在Win 7 Powershell中，输出为：
Fetching package metadata ...
CondaHTTPError: HTTP None None for url <https://conda.anaconda.org/anaconda/win-64/repodata.json>
Elapsed: None
An HTTP error occurred when trying to retrieve this URL.
HTTP errors are often intermittent, and a simple retry will get you on your way.
如何修复此问题并安装pandas-datareader软件包？