[3.14] gh-144694: Fix re.Match.group() doc claiming [1..99] range limit (GH-144696) (#145065)

gh-144694: Fix re.Match.group() doc claiming [1..99] range limit (GH-144696)

The documentation incorrectly stated that numeric group arguments
must be in the range [1..99]. This limit was removed in Python 3.5
(bpo-22437). Replace with "a positive integer" since the next
sentence already documents the IndexError for out-of-range values.
(cherry picked from commit 85021bc2477f3ab394172b6dda3110e59f4777dd)

Co-authored-by: Mohsin Mehmood <55545648+mohsinm-dev@users.noreply.github.com>