Updated FE to display only tenths decimal place for mean
Updated FE to display only tenths decimal place for mean to match the FNIS scores in the consensus summary
Also found that we haven't been doing any score validation to enforce tenths on FNIS updates during consensus. Added this to the endpoint so that any errors are raised to the FE, and added a test to make sure that HTTPBadRequest was returned when trying to update a FNIS with an invalid value.