async function checkForUpdates() {
  try {
    log.info('Check for updates');
    const lastGitUpgradeVersion = await exec('npm view react-native-git-upgrade@latest version');
    const current = require('./package').version;
    const latest = semver.clean(lastGitUpgradeVersion);
    if (semver.gt(latest, current)) {
      log.warn(
        'A more recent version of "react-native-git-upgrade" has been found.\n' +
        `Current: ${current}\n` +
        `Latest: ${latest}\n` +
        'Please run "npm install -g react-native-git-upgrade"'
      );
    }
  } catch (err) {
    log.warn('Check for latest version failed', err.message);
  }
}
If there's a newer version of react-native-git-upgrade in npm, suggest to the user to upgrade.