text: Title: Warn on large files when using resources_
  Body: Users can tell Ploomber to track changes to configuration files via [resources_](https://ploomber.readthedocs.io/en/latest/api/spec.html?highlight=resources_#tasks-params-resources), however, to track changes, we compute a file hash which may take too long if the file is large.
  
  We should show a warning if this happens, `resources_` should not be used with large files.