Python requirement when using Autotools build system

[Apteryks]

Hi,

There's a new dependency on Python in the 0.25 releases, upgrading from 0.24. The GNU build system (Autotools) doesn't check for it, and the build fails like:

p11-kit/proxy.c:729:10: fatal error: p11-kit/proxy-generated.h: No such file or directory
  729 | #include "p11-kit/proxy-generated.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.

Adding python to the build inputs resolves the issue. It should be added as as required program to configure.ac. Also, perhaps the release dist could contain the generated files to avoid the dependency on Python.