Decimals: string to decimal fails if more decimal places than "scale"

[Julian-J-S]

Checks

• [X] I have checked that this issue has not already been reported.
• [X] I have confirmed this bug exists on the latest version of Polars.

Reproducible example

pl.DataFrame({
    'x': ['1', '1.23', '1.2345'],
}).with_columns(
    d=pl.col("x").cast(pl.Decimal(scale=2)),
)

Log output

ComputeError: conversion from `str` to `decimal[*,2]` failed in column 'x' for 1 out of 3 values: ["1.2345"]

Issue description

Converting from str to decimal fails if the str values contain more decimal places than the specified "scale" of the Decimal.

Expected behavior

This works in other libraries (e.g. pyspark) and should also work in polars. Also polars supports casting from f64 "1.2345" to Decimal "1.23"

pyspark:

---

Note: I am opening a lot of Decimal Issues (Decimals are required for many financial calculations where I currently use pyspark). I heard a bigger Decimal update in coming soon? Not sure abount the roadmap but happy to help.

Installed versions

0.20.5