v4.2.0
[SPARK-56186][PYTHON] Retire pypy
[SPARK-37022][PYTHON] Use black as a formatter for PySpark
[SPARK-47683][PYTHON][BUILD] Decouple PySpark core API to pyspark.core package
[SPARK-56018][PYTHON] Use ruff as formatter
[SPARK-55986][PYTHON] Upgrade black to 26.3.1