[FYI] SPARK-47993: Drop Python 3.8

[Dongjoon Hyun]

FYI, there is a proposal to drop Python 3.8 because its EOL is October 2024.

https://github.com/apache/spark/pull/46228
[SPARK-47993][PYTHON] Drop Python 3.8

Since it's still alive and there will be an overlap between the lifecycle
of Python 3.8 and Apache Spark 4.0.0, please give us your feedback on the
PR, if you have any concerns.

>From my side, I agree with this decision.

Thanks,
Dongjoon.