wxWidgets 3.2 provides a Qt frontend in addition to the GTK3 one, so packages have been renamed from wxgtk-* to wxwidgets-*.
The GTK2 frontend is no longer provided. If you have wxgtk2 installed, the upgrade will fail with
error: failed to prepare transaction (could not satisfy dependencies)
:: removing wxgtk-common breaks dependency 'wxgtk-common' required by wxgtk2
In such case, uninstall wxgtk2 first with
# pacman -Rc wxgtk2
and then proceed with the upgrade.