fix: remove unused alembic script

we just use the upstream script now

rattail_demo/db/alembic/env.py

@@ -1,74 +0,0 @@
-# -*- coding: utf-8; mode: python; -*-
-"""
-Alembic environment script
-"""
-
-from alembic import context
-from sqlalchemy.orm import configure_mappers
-
-from rattail.config import make_config
-from rattail.db.util import get_default_engine
-from rattail.db.continuum import configure_versioning
-
-
-# this is the Alembic Config object, which provides
-# access to the values within the .ini file in use.
-alembic_config = context.config
-
-# use same config file for Rattail
-rattail_config = make_config(alembic_config.config_file_name, usedb=False, versioning=False)
-
-# configure Continuum..this is trickier than we want but it works..
-configure_versioning(rattail_config, force=True)
-from rattail_demo.db import model
-configure_mappers()
-
-# needed for 'autogenerate' support
-target_metadata = model.Base.metadata
-
-
-def run_migrations_offline():
-    """Run migrations in 'offline' mode.
-
-    This configures the context with just a URL
-    and not an Engine, though an Engine is acceptable
-    here as well.  By skipping the Engine creation
-    we don't even need a DBAPI to be available.
-
-    Calls to context.execute() here emit the given string to the
-    script output.
-
-    """
-    engine = get_default_engine(rattail_config)
-    context.configure(
-        url=engine.url,
-        target_metadata=target_metadata)
-
-    with context.begin_transaction():
-        context.run_migrations()
-
-
-def run_migrations_online():
-    """Run migrations in 'online' mode.
-
-    In this scenario we need to create an Engine
-    and associate a connection with the context.
-
-    """
-    engine = get_default_engine(rattail_config)
-    connection = engine.connect()
-    context.configure(
-        connection=connection,
-        target_metadata=target_metadata)
-
-    try:
-        with context.begin_transaction():
-            context.run_migrations()
-    finally:
-        connection.close()
-
-
-if context.is_offline_mode():
-    run_migrations_offline()
-else:
-    run_migrations_online()