[3.9] bpo-41412 and bpo-40948: Windows installer updates (GH-21656) by miss-islington · Pull Request #21661 · python/cpython
Prevent installation on Windows 8 and earlier.
Download UCRT on demand when required (non-updated Windows 8.1 only)
Add reference to py launcher to post-install message
(cherry picked from commit 37a06cb)
Co-authored-by: Steve Dower steve.dower@python.org