Narwhals v1.25.1

Changes

🚀 Performance improvements

• perf: use fastpath in DataFrame.to_numpy for pandas, improve performance for DataFrame.schema for pandas, use fewer values to sniff dtype for pandas objects (#1929)

✨ Enhancements

• enh: Deprecate native_namespace in favour of backend in from_dict (#1931)
• feat: validate duplicate column names in pyarrow and duckdb (#1815)

🐞 Bug fixes

• fix: Always collect Iterator[IntoExpr] in utils.flatten (#1934)

📖 Documentation

• docs: Make DataFrame and LazyFrame docstrings shorter and more concise (#1939)
• chore: fix a couple of typos 🙃 (#1921)

🛠️ Other improvements

• ci: fix plotly downstream test (#1938)
• fix(typing): Use IntoDataFrameT in to_native (#1936)
• fix(typing): Use correct TypeVar/Union pairs in from_native (#1935)
• fix(typing): Ensure LazyFrame has a unique TypeVar (#1930)
• refactor: refactoring following refurb and perflint suggestions (#1925)

Thank you to all our contributors for making this release possible!
@DeaMariaLeon, @FBruzzesi, @IsaiasGutierrezCruz, @MarcoGorelli, @dangotbanned, and @raisadz