Squashed commit of the following:

commit f7589d543234b245447a400e73e15cccda607e4d
Author: brian d foy <brian.d.foy@gmail.com>
Date:   Fri Dec 4 17:42:28 2020 -0500

    Strip trailing whitespace from shortcode

    Files always have a trailing newline and that shouldn't be part of
    the output. Hugo has so far denied this is a problem.

    See: gohugoio/hugo#1753