old_contents: version_info = (6, 0, 0, 'dev')
  __version__ = '.'.join(map(str, version_info))
  __frontend_version__ = '~2.0.0-dev'
  
new_contents: version_info = (6, 0, 0, 'dev')
  __version__ = '.'.join(map(str, version_info))
  __frontend_version__ = '^2.0.0'
  
subject: update the frontend version check to ^2.0.0