Update PUT /org endpoint to set when an Org was last active

[jdaigneau5]

Summary

Update the PUT /org endpoint to be accessible to CNAs. When CNAs access this endpoint, it will update a timestamp, showing that the CNA is still active. This is a Secretariat requirement.

Definition of Done

• Update Org model to include new last_active timestamp
• Update PUT /org/{shortname} endpoint to be accessible to CNAs and to update last_active