This is a bug fix release that fixes compatibility issues with Python 3.5 and 3.6 and a missing index due to bad naming.
For new installations make sure to use this latest release. For existing installations an upgrade is not necessary unless you plan to reimport TIGER housenumber data. If you have installed your database with Nominatim 3.7.0, you should add the missing index using the following SQL statement:
CREATE UNIQUE INDEX idx_location_property_tiger_place_id ON location_property_tiger_import (place_id);