use Test::File::SD instead of F::SD::ProjectDistDir

File::SD::PDD looks in the parent directories and decides that
it's running from a work copy if there is a 'lib' directory
in there. Which breaks if, like me, your perlbrew is installed
under '/usr/local/soft/perlbrew' (the '/usr/local/lib' will trigger
the "Hey! /usr/local/ is our work dir" check)

Test::File::SD only fudges things for the tests, and is safer.