text: Title: API not capturing conversion_id property update
  Body: ### Describe the problem/bug
  
  When converting an input measurement the 'conversion_id' prop of "device measurement settings" in the API stays null while the db reflects the update
  
  ### Versions:
  
   - Mycodo Version: 8.10.1
   - Raspberry Pi Version: 3B+
   - Raspbian OS Version: Raspberry Pi OS Lite
  
  ### Reproducibility
  
  Convert an input measurement via UI
  GET api/settings/device_measurements/by_device_id/[unique_id]
  Bug: DB has conversion_id ref but API does not
  
  thank you 
  
  