[BUG] Dart code generator does not support date format for string

Created by: dalewking

Description

The dart code generator does support date-time format for strings, making the parameter type DateTime and formatting it correctly. However if the format for a string is "date" it also uses DateTime for the parameter, but it does not format it correctly as it includes the time in the formatted version.

openapi-generator version

4.0.0-beta3