Fix CI badge in readme

[pyaillet]

Fixes #52

Description

Used the create badge in github action to report the status of the build workflow for the default branch (master)

Motivation and Context

• I have raised an issue to propose this change (required)

How Has This Been Tested?

The README is showing the status of the last build workflow for the default branch (master)

Types of changes

• 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)

Impact to existing users

Nothing

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've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

Approved

[alexellis]

Thank you for your contribution