Replace Travis with Github Actions

Description

Migrated existing Travis to Github Actions Add CI for Ubuntu 20.04 Python 3 Add Workaround # pylint: disable=import-error for pylint conditional imports with six Issue has been documented in the pylint repository

At a later date workflows the workflows will be simplified.

Motivation and Context

From @kendonB Travis is on the way out soon ropensci.org/technotes/2020/11/19/moving-away-travis

We should try and transition to GA soon

Travis has also been known to break repeatedly along with a few bugs with publishing packages. The only downside is the project CI being tied to Github ecosystem. Github Actions allows us to do four congruent instances CI.

How Has This Been Tested

Github Actions configuration is been tested with Windows 10 Python 2.7.18 and 3.6.8 Mac OS Python 3.6.8 Ubuntu 20.04 Python 3.6.8

Types of changes

[x] Docs change / refactoring / dependency upgrade
[x] Bug fix (non-breaking change which fixes an issue or bug)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to change)
[ ] Renamed existing command phrases (we discourage this without a strong rationale).

Checklist

[x] I have read the CONTRIBUTING document.
[x] My code follows the code style of this project.
[ ] I have checked that my code does not duplicate functionality elsewhere in Caster.
[ ] I have checked for and utilized existing command phrases from within Caster (delete if not applicable).
[x] My code implements all the features I wish to merge in this pull request.
[ ] My change requires a change to the documentation.
[ ] I have updated the documentation accordingly.
[x] I have added tests to cover my changes.
[x] All new and existing tests pass.

Maintainer/Reviewer Checklist

[x] Basic functionality has been tested and works as claimed.
[ ] New documentation is clear and complete.
[x] Code is clear and readable.

dictation-toolbox / Caster