gh-104992: [What's New in 3.12] Document unittest.TestProgram.usageExit's deprecation#104995

hugovk merged 2 commits intopython:mainpython/cpython:mainfrom

hugovk:docs-unittest.TestProgram.usageExit-whatsnew312-deprecationshugovk/cpython:docs-unittest.TestProgram.usageExit-whatsnew312-deprecationsCopy head branch name to clipboard