Add database setup

src/compub/db.py

@@ -0,0 +1,9 @@
+from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
+from sqlalchemy.orm import declarative_base, sessionmaker
+
+from compub.settings import settings
+
+
+engine = create_async_engine(settings.db_uri, future=True)
+LocalAsyncSession = sessionmaker(engine, expire_on_commit=False, class_=AsyncSession)
+ORMBase = declarative_base()