setup: fix the py2exe logic to work with py3 TortoiseHg still uses (the modernized) py2exe packaging, but the build was failing since `py2exe.Distribution` was removed. One thing to note is that later in this module, there's a hack to include `distutils` when building from a virtualenv. While `import distutils` works in `hg debugshell` when built with py2, it doesn't work in py3. I'm not sure why- I don't see it in `library.zip` either. It doesn't seem to break anything though. Differential Revision: https://phab.mercurial-scm.org/D12553

--- a/setup.py	Wed Apr 13 07:58:49 2022 -0700
+++ b/setup.py	Wed Apr 13 14:25:13 2022 -0400
@@ -197,7 +197,7 @@
 try:
     import py2exe
 
-    py2exe.Distribution  # silence unused import warning
+    py2exe.patch_distutils()
     py2exeloaded = True
     # import py2exe's patched Distribution class
     from distutils.core import Distribution