net/samba422: Fix pkg-plist when building without PYTHON3

The build fails at the packaging step because it tries to
include a file that doesn't exist without PYTHON3.

PR: 290439
Reported by: Toshimichi Masubuchi
Sponsored by: Klara, Inc. (0mp)
Co-authored-by: Toshimichi Masubuchi <t.masub@gmail.com>