Pre-Release of Polars 2.0

Polars 2.0’s first release candidate makes the streaming engine the default for all LazyFrame queries, delivering up to five-times faster execution and markedly lower memory consumption, though row order is no longer guaranteed unless maintain_order=True is set. The update also enforces stricter error handling, raising type-mismatch exceptions—such as disallowing is_in between Int64 and Float64—so schema issues surface early in the pipeline.