replacing return HTTPException with raise (#134)

Problem
Fastapi standard is to use raise instead of return

Solution
there was only one instance (that I could find) where we used return instead of raise

Ticket URL
https://mediform.atlassian.net/browse/MEDI-46

Documentation
NA

Tests Run
make testapi

app/api/main/auth.py

@@ -85,7 +85,7 @@ def generate_auth_token(
 
 def get_credentials_exception() -> HTTPException:
 
-    return HTTPException(
+    raise HTTPException(
         status_code=status.HTTP_401_UNAUTHORIZED,
         detail="Could not validate credentials",
         headers={"WWW-Authenticate": "Bearer"},