gh-150791: add critical section for groupby.next#150792

KowalskiThomas wants to merge 3 commits into

python:mainpython/cpython:mainfrom

KowalskiThomas:kowalski/fix-critical-section-for-groupby-nextKowalskiThomas/cpython:kowalski/fix-critical-section-for-groupby-nextCopy head branch name to clipboard