getPackageManagerFromLockFile = () => {
  const packageLockExists = doesFileExist('package-lock.json')
  const yarnLockExists = doesFileExist('yarn.lock')

  if (packageLockExists && yarnLockExists) return undefined
  if (packageLockExists) return 'npm'
  if (yarnLockExists) return 'yarn'
  return undefined
}
Returns the package manager from the lock file

@returns {String} packageManger or undefined