CITI training was set to expire after 1095 days (`valid_duration=datetime.timedelta(days=1095)`)

[tompollard]

We are now able to set a "valid_duration" for different training types. We had intended to set this to None for PhysioNet CITI training, meaning training would never expire.

After checking the database, I noticed that the valid_duration had been set to 1095 days. This means that training may have expired for users who submitted their training ~3 years ago.

I have set the valid_duration for CITI training to None, so training will not expire now. I need to look into whether this has any negative downstream consequences (e.g. some users may now have two active training reports).