Enable ppc64le

Previously closed discussion: https://github.com/actions/setup-python/issues/613

Description:
Build python binaries for ppc64le and enable support for ppc64le in this repo.

Justification:
We recently launched GitHub Actions so open source projects can use runners on our Power and Z hardware. At this point, we are onboarding projects to use our GitHub actions service. Here is a blog post about our announcement and our official GitHub repo is located here.

This would greatly benefit a lot of open source communities to have the python action runner be supported on ppc64le. My goal is to eliminate inconsistencies with ppc64le and have parity with other archs (like with our newly released github actions).

Are you willing to submit a PR?
Yes absolutely. We can assist with any development, testing, and other needs if this feature request can be included in a roadmap.

首先阅读 actions/setup-python#613 中之前已关闭的讨论，然后定位此仓库的 build 和 release 入口点；issue 未指明任何文件或测试。完成的标准是为 ppc64le 构建 Python 二进制文件，并且 action 支持该架构，同时为新路径提供 coverage。