CSPE

This release introduces several performance improvements, new features like Iceberg schema evolution and correlated subqueries, and numerous bug fixes. It also deprecates the `rechunk` parameter and related functions.

This release focuses heavily on performance improvements across group-by operations, native aggregations, and data parsing, while stabilizing Decimal support and introducing several new features like ewm_mean in streaming and enhanced list/array aggregations. Two functions, Expr.agg_groups() and pl.groups(), have been deprecated.

This release focuses heavily on performance improvements across group-by operations, data serialization, and string parsing. Numerous enhancements were added, including new aggregation methods and improved ADBC engine integration, alongside fixes for various edge cases and regressions.