[API] PUT/PATCH requests not updating instrument flags

[AlexandraLivadas]

Describe the bug
Both the PUT and PATCH requests used to update an instrument's flag values (and DDE flag values) are returning internal server errors and not correctly updating the values
The 4 requests in question are:

• PUT /candidates/{candid}/{visit}/instruments/{instrument}/flags
• PATCH /candidates/{candid}/{visit}/instruments/{instrument}/flags
• PUT /candidates/{candid}/{visit}/instruments/{instrument}/dde/flags
• PATCH /candidates/{candid}/{visit}/instruments/{instrument}/dde/flags

To Reproduce

1. Go to the API Documentation module and scroll down to any of the above commands
2. Click on "Try it out" and enter a CandID, visit label, and instrument name. You can use the above GET requests to get a candidate and the list of their visits and instruments
3. Fill in the request body with the flag data you would like to update
4. Click on "Execute" and see internal server error
5. Go to the GET request /candidates/{candid}/{visit}/instruments/{instrument}/flags (right above the PUT request) and insert the same CandID, visit label, and instrument. Execute and see that the flag data was not updated.

What did you expect to happen?
The flag information for that candidate's instrument should be updated and there should be no error.