Release version for SQLAlchemy 1.4

[fmigneault]

Hi @ergo

I encountered the following error with new SQLAlchemy==1.4

>Textual column expression 'depth' should be explicitly declared with text('depth'), or use column('depth') for more specificity

when reaching the following code ziggurat_foundations.models.services.resource_tree_postgres.ResourceTreeServicePostgreSQL.from_parent_deeper

query = db_session.query(cls.model, "depth", "sorting", "path")

I see that you have already pushed the needed fix (add column()). Thanks for the quick patch! Is it possible to have a new version released soon?