bpo-35766: Change format for feature_version to (major, minor) (GH-13992) (GH-13993)

(A single int is still allowed, but undocumented.)

https://bugs.python.org/issue35766
(cherry picked from commit 10b55c1643b512b3a2cae8ab89c53683a13ca43e)

Co-authored-by: Guido van Rossum <guido@python.org>
4 files changed