text: Title: SQLALchemy support for Composite Primary Key/Different index
  Body: I was looking at the implementation for SQLAlchemy and noticed that it takes only the first primary key of the table 
  
  https://github.com/awtkns/fastapi-crudrouter/blob/master/fastapi_crudrouter/core/sqlalchemy.py#L50
  
  What if I have a composite primary key in my table?