fix: importing the package no longer asks setuptools for a namespace

The first statement of __init__.py called pkg_resources.declare_namespace, and
setuptools 83 no longer ships pkg_resources, so importing datastore_orm raises
ModuleNotFoundError before any of its own modules load. Every consumer dies on
`import datastore_orm`; in Insights that is Django app startup, which takes the
image build down with it.

The declaration was for the `infi` namespace this distribution used to live
under — buildout.cfg still names that as the namespace package. The code now
ships one plain top-level package, src/datastore_orm, so there is no namespace
left to declare and the call could only ever fail. Removing it is what makes the
package importable again, not a workaround for the missing module.

src/datastore_orm/__init__.py

@@ -1,5 +1,3 @@
-__import__("pkg_resources").declare_namespace(__name__)
-
 from datastore_orm.database import *
 from datastore_orm.engines import *
 from datastore_orm.fields import *