### What changes were proposed in this pull request?
`datetime` is already imported a few lines below :)
ce27cc54c1/python/pyspark/sql/tests/test_pandas_udf_scalar.py (L24)
### Why are the changes needed?
This is the last instance of the duplicate import.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Manual.
Closes#29109 from Fokko/SPARK-32311.
Authored-by: Fokko Driesprong <fokko@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>