Polars: py-0.15.13 Release

✨ Enhancements

• Improve iterating over GroupBy (#6051)
• much faster lazy type-checks (#6064)
• support array-expansion of scalars on frame init from dict (#6034)
• improve error message when writing nested data to… (#6040)

🐞 Bug fixes

• bound complex type from 3.8 to 3.11 (#6071)
• deal with unnest schema expansion in projection pd (#6063)
• correct output dtype for cummin/cumsum/cummax (#6062)
• block streaming on literal series/range (#6058)
• improve handling of dict-type "columns" param on frame-init (#6045)
• Fix typing for DataFrame.select (#6047)
• ndjson struct inference (#6049)
• fix stringcache. latest refactor introduced a hashing error (#6056)
• allow mixed field order and availability in apply that r… (#6041)
• deal with empty structs (#6039)
• fix aggregation that filters out all data (#6036)
• fix diff overflow (#6033)
• keep column names in is_null/is_not_null (#6032)
• keep name when sorting categorical in lexial order (#6029)
• tweaked property/accessor behaviour (#6021)
• properly set null anyvalue if categorical is neste… (#6025)
• Fix from_epoch function signature (#6024)
• Validate estimated_size parameter (#6018)

🛠️ Other improvements

• suggest forward fill in cumsum/cummax (#6061)
• Fix SIM105 issues. (#6042)
• Remove trailing spaces in glimpse output (#6037)
• Remove unnecessary noqa's (#6035)
• Fix flake8-pytest-style errors in tests. (#6031)
• update read_sql and row docstrings (#6028)
• Enable the isort-style import autofix via ruff (#6020)
• Update py-polars/Cargo.lock (#6013)
• Refactor pivot tests (#6012)
• Use ruff instead of isort, flake8 and pyupgrade (#5916)
• Properly deprecate groupby.pivot (#6000)

Thank you to all our contributors for making this release possible! @alexander-beedie, @ghuls, @ritchie46, @stinodego and @universalmind303