Polars: py-0.19.15 Release

⚠️ Deprecations

• Rename str.json_extract to str.json_decode (#12586)

🚀 Performance improvements

• apply left side predicate pushdown also to right side on semi join (#12565)
• ensure streaming parquet download remains concurrent ~7x (#12552)

✨ Enhancements

• warn if by column is not sorted in rolling aggregations (as opposed to raising), add warn_if_unsorted argument (#12398)
• struct -> json encoding expression (#12583)
• Implement support for multi-character comments in read_csv (#12519)
• Implement LazyFrame.sink_ndjson (#10786)
• use JEMALLOC on all unix architectures (#12568)
• improve concurrency parameters (#12567)
• In explain(), rename PIPELINE to STREAMING so it's clearer what it means (#12547)

🐞 Bug fixes

• error when invalid list to array is given (#12584)
• parquet: do not extend existing nested that is already complete (#12569)
• accidental panic if predicate selects no files (#12575)
• fix lazy parquet slice with nested columns (#12558)
• ensure stats-evalutor exists (#12566)
• list schema of list eval (#12563)
• ensure concurrency budget never locks (#12555)
• Fix lazy schema for group_by_dynamic and rolling (#12551)
• address overflow on vec capacity calculation for int_ranges with negative step (#12548)

🛠️ Other improvements

• convert all recursive parquet deserialize to iterative (#12560)
• Minor cleanup in Expr class (#12549)

Thank you to all our contributors for making this release possible! @MarcoGorelli, @Qqwy, @alexander-beedie, @dmitrybugakov, @fernandocast, @gab23r, @itamarst, @nameexhaustion, @ritchie46, @stinodego and @uchiiii