From the terminal, run this:
git checkout master
git branch -m master main
git fetch
git branch --unset-upstream
git branch -u origin/main
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main
Every person who has the repository cloned on their local machine will have to run:
git pull
git checkout main
git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/main
git branch -D master