feat(sources): generate .git_archival.txt for setuptools-scm builds#962

LalatenduMohanty wants to merge 1 commit intopython-wheel-build:mainpython-wheel-build/fromager:mainfrom

LalatenduMohanty:961_git-archival-for-setuptools-scmLalatenduMohanty/fromager:961_git-archival-for-setuptools-scmCopy head branch name to clipboard