Consider __slots__

[v1gnesh]

Came across this blog post today - https://dev.arie.bovenberg.net/blog/finding-broken-slots-in-popular-python-libraries/.
It talks about __slots__.
Here's an example of SQLAlchemy benefitting from it - https://docs.sqlalchemy.org/en/20/changelog/migration_10.html#significant-improvements-in-structural-memory-use

Don't know how feasible it is for dagster, but just thought I'd bring it up for discussion/assessment.