Make sure all certified datasets are fine

[zelima]

Some of the certified datasets have validation errors eg https://datahub.io/core/population-growth-estimates-and-projections If dataset is certified it should not have any kind of errors

Acceptance Criteria

• No certified dataset with errors

Tasks

• List all certified datasets and check the status
• investigate the reason why some of them fail
• fix if possible
  • remove form certified list if not