Fix assumption that python is called python

The assumption was introduced by 7e674a887d, where find_program('python') was used instead of Meson's built-in python discovery services. This turned out to be a bad idea because of course there are systems in 2024 where python is not python 3.

resources/meson.build

@@ -49,7 +49,7 @@ if host_platform == 'windows'
 		}
 		foreach key, icons : win_icos
 			command = [
-				find_program('python'),
+				python3_prog,
 				join_paths(meson.current_source_dir(), 'make-ico.py'),
 				'@OUTPUT@',
 			]