Polars: py-0.20.18 Release

🚀 Performance improvements

• CSV reading memory usage tests and fixes (#15422)
• avoid double-allocation in rolling_apply_agg_window (#15423)
• Make LogicalPlan immutable (#15416)
• Add non-order preserving variable row-encoding (#15414)
• Use row-encoding for multiple key group by (#15392)

✨ Enhancements

• Supports explode_by_offsets for decimal (#15417)
• Add read_clipboard and DataFrame.write_clipboard (#15272)
• Add null_on_oob parameter to expr.list.get (#15395)
• make Series.__bool__ error message Rusttier (#15407)
• CSV-writer escape carriage return (#15399)

🐞 Bug fixes

• datetime operations (e.g. .dt.year) were raising when null values were backed by out-of-range integers (#15420)
• Ensure Binary -> Binview cast doesn't overflow the buffer size (#15408)
• Don't prune alias in function subtree (#15406)
• Return 0 for n_unique() in group-by context when group is empty (#15289)
• Unset UpdateGroups after group-sensitive expression (#15400)
• to_any_value should supports all LiteralValue type (#15387)
• Hash failure combining hash of two numeric columns containing equal values (#15397)
• Add FixedSizeBinary to arrow field conversion (#15389)
• Conversion of expr_ir in partition fast path (#15388)
• fix panic when doing a scan_parquet with hive partioning (#15381)
• sort for series with unsupported dtype should raise instead of panic (#15385)

📖 Documentation

• Added example for explode mapping strategy in pl.Expr.over (#15402)
• Add outer_coalesce join strategy in the user guide (#15405)
• Change the example to series for series/array.py (#15383)
• Add "See Also" for arg_sort and arg_sort_by (#15348)

🛠️ Other improvements

• make dsl immutable and cheap to clone (#15394)
• use recursive crate, add missing recursive tag (#15393)
• Update CODEOWNERS (polars-sql) (#15384)

Thank you to all our contributors for making this release possible! @CanglongCl, @JamesCE2001, @MarcoGorelli, @Sol-Hee, @alexander-beedie, @dependabot, @dependabot[bot], @itamarst, @kszlim, @mcrumiller, @nameexhaustion, @orlp, @reswqa, @ritchie46, @rob-sil and @thomaslin2020