feature(avatar-shape): add option for avatar shape

[BobAnkh]

Description

Add an option to choose the avatar shape.

• [x] add a new parameter in action. Round for round avatar and square for square avatar. Default set to square
• [x] use format string to construct the html template for contributor list

How Has This Been Tested?

Test with flake8 and format with yapf

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• [x] Code follows the code style of this project.
• [x] Changes follow the CONTRIBUTING guidelines.
• [x] Update necessary documentation accordingly.
• [x] Lint and tests pass locally with the changes.
• [x] Check issues and pull requests first. You don't want to duplicate effort.

Other information

[boring-cyborg[bot]]

Thanks for your first pull request!

[boring-cyborg[bot]]

Awesome work, congrats on your first merged pull request!

[github-actions[bot]]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue or pull request.