Sometimes wxWidgets increments the subrelease to a non-zero value, and
since wxPython will report a subrelease, we must ensure we can get the
subrelease from the wx library properly, otherwise configure will fail
thinking the library isn't the same version as that used by wxPython.
Fixes: https://gitlab.com/kicad/code/kicad/-/issues/13887
(Cherry-picked from b536580119)
