[3.11] gh-94777: Fix deadlock in ProcessPoolExecutor (GH-94784) (#106607)

gh-94777: Fix deadlock in ProcessPoolExecutor (GH-94784)

Fixes a hang in multiprocessing process pool executor when a child process crashes and code could otherwise block on writing to the pipe.  See GH-94777 for more details.
(cherry picked from commit 6782fc050281205734700a1c3e13b123961ed15b)

Co-authored-by: Louis Paulot <55740424+lpaulot@users.noreply.github.com>