async function gitCheckout(branch, create, execaOptions) {
  await execa("git", create ? ["checkout", "-b", branch] : ["checkout", branch], execaOptions);
}
Checkout a branch on the current git repository.

@param {String} branch Branch name.
@param {Boolean} create to create the branch, `false` to checkout an existing branch.
@param {Object} [execaOpts] Options to pass to `execa`.