Learn how to test in Fedora against system/RPM gem dependencies

[apjanke]

Learn how to test on Fedora against gems (nokogiri, mustache, etc) installed with the Fedora-distributed RPMs instead of using bundler. So we can test how ronn will run in the context of the RPM-supplied dependencies, like how it will when Fedora builds it as an RPM. Without having to figure out how to mimic the RPM builds of gems in installations to our rbenv Rubies.

Installing the RPM deps is easy enough, but I don't know how to load them in to the ruby execution for ronn. Learn how to do that. Have a look at the stuff in the existing RPM package for ronn-ng.

Follows up discussion in #102 and #107.

Work for this is on branch WIP/fedora-testing.

[apjanke]

Looks like you don't need to do anything to load the gems installed via RPMs; they're just available by default in the system ruby. So you can just install those and then run rake test without the bundle exec part. Tried that now on Fedora 39 and it's passing. Added notes about it to the doco in the repo at dd2ceeb.