how to change my default branch in git
'settings' >> 'Code and Automation' >> 'Branches' >> 'Default Branch'
On GitHub.com, navigate to the main page of the repository.
Under your repository name, click "Settings".
In the "Code and automation" section of the sidebar, click "Branches".
Under "Default branch", to the right of the default branch name, click.
Use the drop-down, then select a branch name.
source: 'https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/managing-branches-in-your-repository/changing-the-default-branch#changing-the-default-branch'