dt.truncate may panic on non-existent datetimes

[MarcoGorelli]

Checks

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

Reproducible example

import polars as pl
from datetime import datetime

pl.Series([datetime(2020, 3, 29, 2, 1)]).dt.replace_time_zone('Europe/London').dt.truncate('46m')

Log output

thread '<unnamed>' panicked at crates/polars-time/src/windows/duration.rs:468:85:
called `Result::unwrap()` on an `Err` value: ComputeError(ErrString("datetime '2020-03-29 01:42:00' is non-existent in time zone 'Europe/London'. Non-existent datetimes are not yet supported"))
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Traceback (most recent call last):
  File "/home/marcogorelli/scratch/t.py", line 4, in <module>
    pl.Series([datetime(2020, 3, 29, 2, 1)]).dt.replace_time_zone('Europe/London').dt.truncate('46m')
  File "/home/marcogorelli/scratch/.venv/lib/python3.11/site-packages/polars/series/utils.py", line 107, in wrapper
    return s.to_frame().select_seq(f(*args, **kwargs)).to_series()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/marcogorelli/scratch/.venv/lib/python3.11/site-packages/polars/dataframe/frame.py", line 8141, in select_seq
    return self.lazy().select_seq(*exprs, **named_exprs).collect(_eager=True)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/marcogorelli/scratch/.venv/lib/python3.11/site-packages/polars/lazyframe/frame.py", line 1934, in collect
    return wrap_df(ldf.collect())
                   ^^^^^^^^^^^^^
pyo3_runtime.PanicException: called `Result::unwrap()` on an `Err` value: ComputeError(ErrString("datetime '2020-03-29 01:42:00' is non-existent in time zone 'Europe/London'. Non-existent datetimes are not yet supported"))

Issue description

this should raise a proper error

Expected behavior

this should raise a proper error

Installed versions

--------Version info---------
Polars:               0.20.14
Index type:           UInt32
Platform:             Linux-5.15.146.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
Python:               3.11.7 (main, Dec  8 2023, 18:56:58) [GCC 11.4.0]

----Optional dependencies----
adbc_driver_manager:  <not installed>
cloudpickle:          <not installed>
connectorx:           <not installed>
deltalake:            <not installed>
fastexcel:            <not installed>
fsspec:               <not installed>
gevent:               <not installed>
hvplot:               0.9.2
matplotlib:           <not installed>
numpy:                1.26.4
openpyxl:             <not installed>
pandas:               2.1.0
pyarrow:              15.0.0
pydantic:             2.6.1
pyiceberg:            <not installed>
pyxlsb:               <not installed>
sqlalchemy:           <not installed>
xlsx2csv:             <not installed>
xlsxwriter:           <not installed>