Narwhals v1.8.1

Changes

• Bug: add conversion from slice to array for selecting rows in pyarrow __getitem__ (#978)
• Debug nightly (#964)

✨ Enhancements

• feat: add DataFrame.sample method (#975)
• feat: add seed to Expr|Series.sample (#974)

📖 Documentation

• doc: Remove unnecessary paragraph in complete_example.md (#969)

🛠️ Other improvements

• test: remove xfail for cudf_constructor on str_to_uppercase test (#976)
• chore: some TODO's cleanup (#970)
• test: xfail cuDF tests that use iteration (#967)
• ci: fixup nightlies (#966)
• ci: only run nightlies on pushes to main (#965)
• ci: enable uv cache, use astral-sh official action (#956)

Thank you to all our contributors for making this release possible!
@FBruzzesi, @LiamConnors, @MarcoGorelli, @aidoskanapyanov, @luke396 and @raisadz