目前Miniconda3的主要版本已经不支持python3.6，以Windows为例，在官网Miniconda — Conda documentation中只有python3.7及以上版本的安装支持，如果想python3.6需要找历史版本。
根据Miniconda3的更新说明，4.5.11是第一个使用python3.7的版本，也即之前的版本即是使用python3.6，例如下图中的Miniconda3-4.5.1版本。
历史版本链接：Index of / (anaconda.com)
参考：Which version of Miniconda has Python 3.6 for Windows 64-bit? - Stack Overflow
I wanted to find the last package in the 3.6 series, so I found the announcement of the python 3.7 package build (September 4, 2018) and then looked that package up by date in https://repo.continuum.io/miniconda/ (Miniconda3-4.5.11), then traced it back one release. The end result:
Miniconda3-4.5.4 was the last Python 3.6 miniconda package.
Miniconda3-4.5.11 is the first that uses 3.7.
There are no releases 4.5.5->4.5.10 in that repository.