[BE][CI] - add a github PR template and CI workflow migration

[aclegg3]

Motivation and Context

This PR adds the PR template used here as well as a github workflow config to replace the current circleci workflow.

How Has This Been Tested

CI

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[0mdc]

LGTM!