Do not exclude Puppet As a Library (PAL) from pkg-plist

PAL was introduced in 5.4.0, is under developement, and has some
pre-documentation available online:
https://docs.google.com/document/d/1rAIo2ApqyLdHdaNkewHp3iTYqVGmRsaY6iG9W-4CJrQ/edit

With hat: puppet