textproc/scancode-toolkit: Fix runtime errors

Relax the version requirements for devel/py-future and textproc/py-pygments.

scancode-toolkit is not (yet) compatible with devel/py-click 7.x thus switch
back to devel/py-click6 for a while.

Also while I'm here:

• Pet portlint (whitespace)

Approved by: mentors (implicit)