Re-do of #199 and #204. Thanks @cclauss for getting the ball rolling for the 3.14 release cycle. Also ping @graingert.

I need to drop Python 3.7 support to use cibuildwheel 3, which is needed for Python 3.14 support.

Once this is merged I'll issue a followup to add support and testing for 3.13, 3.14, and 3.14t. I already have that set up on a different branch in my fork and CI is passing. I extracted this somewhat more minimal change as requested over in #204.

ping @sethmlarson