Deprecating windows 32bit support

[IAlibay]

As noticed recently, the 32bit windows azure runner has been failing.

This appears to stem from a mix of the recent scipy 1.9.2 release which no longer providing win32 wheels, and azure not providing a suitable toolchain for compiling a 32bit version of scipy.

A deeper conversation on this can be seen here: https://discuss.scientific-python.org/t/releasing-or-not-32-bit-windows-wheels/282

As a consequence, it appears (and this is what I've been told on the scientific-python scipy channel - @tylerjereddy may correct me here), that scipy is going ahead with dropping win32 support completely.

Overall I see this as a good opportunity to consider also aiming to drop 32bit support completely in the near future.

At worst we should drop support once scipy 1.9.1 is no longer supported, so ~ 2 years from now?

Pinging @tylerjereddy for further comments here on the situation re: scipy and 32bit