.dt.truncate may return incorrect results for pre-1970 dates

[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

In [26]: In [1]: import polars as pl
    ...:
    ...: In [2]: from datetime import date, datetime
    ...:
    ...: In [3]: s = pl.Series([datetime(1980, 1, 1), datetime(1969,1,1,1)])
    ...:
    ...: In [4]: s.dt.truncate('1d')
Out[26]:
shape: (2,)
Series: '' [datetime[μs]]
[
        1980-01-01 00:00:00
        1969-01-03 00:00:00
]

Log output

No response

Issue description

the second one is wrong

Expected behavior

shape: (2,)
Series: '' [datetime[μs]]
[
        1980-01-01 00:00:00
        1969-01-01 00:00:00
]

Installed versions

--------Version info---------
Polars:               1.1.0
Index type:           UInt32
Platform:             Linux-5.15.153.1-microsoft-standard-WSL2-x86_64-with-glibc2.35
Python:               3.11.9 (main, Apr  6 2024, 17:59:24) [GCC 11.4.0]

----Optional dependencies----
adbc_driver_manager:  <not installed>
cloudpickle:          3.0.0
connectorx:           <not installed>
deltalake:            <not installed>
fastexcel:            <not installed>
fsspec:               2024.3.1
gevent:               <not installed>
great_tables:         0.7.0
hvplot:               0.10.0
matplotlib:           3.8.4
nest_asyncio:         1.6.0
numpy:                1.26.4
openpyxl:             <not installed>
pandas:               2.2.2
pyarrow:              16.1.0
pydantic:             <not installed>
pyiceberg:            <not installed>
sqlalchemy:           <not installed>
torch:                <not installed>
xlsx2csv:             <not installed>
xlsxwriter:           <not installed>

[MarcoGorelli]

Noticed this while writing a hypothesis test

fix incoming