ci: switch to using 'main' as the default branch

[pcattori]

↪️ Pull Request

See https://github.com/github/renaming

Resolves #467

[github-actions[bot]]

:tada: This PR is included in version 1.3.0 :tada:

The release is available on:

• v1.3.0
• GitHub release

Your semantic-release bot :package::rocket: