Integrates Github Actions

[manrajgrover]

Description of new feature, or changes

This PR removes Travis and Appveyor integrations in favor of Github Actions.

Checklist

• [x] Your branch is up-to-date with the base branch
• [x] You've included at least one test if this is a new feature
• [x] All tests are passing

Related Issues and Discussions

People to notify

None

[manrajgrover]

Test cases are failing for Python versions >= 3.8. Will be fixed in a separate MR.