CI: migrate from travis-ci

[prjemian]

Since travis-ci is changing its pricing model, find another CI service that fits the budget of this project

• [x] Identify alternative: GitHub Actions
• [x] setup CI process
• [x] build for all python versions ['2.7', '3.6', '3.7', '3.8']
• [x] CI status: badging
• [x] drop travis-ci

[prjemian]

Try Github Actions

see https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions

[prjemian]

Follow Python Package using Anaconda from https://github.com/prjemian/pyRestTable/actions/new

[prjemian]

https://github.com/actions/starter-workflows/blob/d9b22d32d233c8ec1ae4cd6a8d06b23c795a816c/ci/python-package-conda.yml

[prjemian]

Need to learn how to setup miniconda with GH Actions

[prjemian]

Need to learn how to test with different python versions

[prjemian]

Aha! The new code uses pytest but existing CI uses unittest. Good that pytest can run these anyway without immediate need to refactor!

[prjemian]

see: https://github.com/marketplace/actions/setup-miniconda

also: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/migrating-from-travis-ci-to-github-actions

[prjemian]

Python 2.7 is EOL, don't test for it. Problems building for Py3.5, don't test for it.

[prjemian]

travis-ci is a webhook. https://github.com/prjemian/pyRestTable/settings/hooks