Implement github-actions-badge directly in shields.io

[dougnukem]

Would it make more sense for this badge implementation to be part of the shields.io project itself. I can help adapting it to their structure from the lambda function.

• Badge request: GitHub actions badges/shields#2574
• https://github.com/badges/shields/blob/master/CONTRIBUTING.md

[kddnewton]

Closing this issue because I'm actually going to shut this down in favor of GitHub's baked-in one (https://github.com/{github_id}/{repository}/workflows/{workflow_name}/badge.svg).