0.3.0 Third Release

Update type handling and introduce DefaultValue and FixedValue types

Modified type handling flow to support new DefaultValue and FixedValue types. Several types and specifications were added or updated as a part of this change. Also, the DatabaseSchemaPostgresBody and TypeMapBody classes were updated to accommodate the changes and ensure compatibility with the new types. Implemented corresponding modifications in the CreateValueObject class. The change also improves optional type handling and updates some dependencies.