math/py-narwhals: Add py-narwhals 1.4.2

Narwhals is an extremely lightweight and extensible compatibility layer between
dataframe libraries!

• Full API support: cuDF, Modin, pandas, Polars, PyArrow
• Interchange-level support: Ibis, Vaex, anything else which implements the DataFrame Interchange Protocol

Seamlessly support all, without depending on any!

• Just use a subset of the Polars API, no need to learn anything new
• Zero dependencies, Narwhals only uses what the user passes in so your library can stay lightweight
• Separate lazy and eager APIs, use expressions
• Support pandas' complicated type system and index, without either getting in the way
• 100% branch coverage, tested against pandas and Polars nightly builds
• Negligible overhead, see overhead
• Let your IDE help you thanks to full static typing, see typing
• Perfect backwards compatibility policy, see stable api for how to opt-in