SQLAlchemy API change in 1.4 breaks type hints

[branen]

https://docs.sqlalchemy.org/en/14/changelog/migration_14.html#change-result-14-core

This change breaks the type hint for materialize_result_proxy in graphql_compiler.compiler.sqlalchemy_extensions.

Since Result seems to be backwards-compatible with ResultProxy, we can probably support the 1.3 and 1.4 APIs in parallel without much mess, but we should probably update our naming to be consistent with the 1.4 object model (e.g. materialize_result_proxy to materialize_result) and make sure that nothing else broke between 1.3 and 1.4.