mix deps HEX_HTTP_CONCURRENCY=1 HEX_HTTP_TIMEOUT=120 timeout

mix  deps.get  timeout 问题：

If this happens consistently, adjust your concurrency and timeout settings:

    HEX_HTTP_CONCURRENCY=1 HEX_HTTP_TIMEOUT=120 mix deps.get

解决方法：

HEX_HTTP_CONCURRENCY=3 HEX_HTTP_TIMEOUT=1200 mix deps.get 

备注：实际上就是使用环境变量