BUG: Fix groupby quantile segfault
Validate that q is between 0 and 1.

Closes #27470
LGTM Thanks @TomAugspurger  Going through the 0.25.3 release the test for this showed up in the diff while cherry-picking. On a second review I don't think this was fully back ported (?). I see the whatsnew note but not the test or the changes to groupby.pyx

Unless I am overlooking something should I pick this up for the 0.25.3 release as well?