Fix missing created_at in TokenGeneration

[k9845]

Addresses

• https://github.com/IFRCGo/go-api/issues/2147
• https://github.com/IFRCGo/go-web-app/issues/1009

Changes

• Add created_at in validated_data

Checklist

Things that should succeed before merging.

• [ ] Updated/ran unit tests
• [ ] Updated CHANGELOG.md

Release

If there is a version update, make sure to tag the repository with the latest version.

[k9845]

@szabozoltan69 let's merge and deploy this to staging.

[k9845]

@szabozoltan69 Can you please merge this to staging?