- Only pull in the distro default ruby version; as hawk only
consumes, but does not produce any rubygems, there is no need to
depend on more than one ruby version.
+ %define rb_build_versions %rb_default_ruby

The existing package in Tumbleweed has waaay to large deps, as it pulls in
Ruby 2.6 AND 2.7:
> zypper info --requires hawk2 | grep ruby
/usr/bin/ruby.ruby2.7
rubygem(ruby:2.6.0:bundler)
rubygem(ruby:2.7.0:bundler)
rubygem(ruby:2.6.0:rails:6.0)
rubygem(ruby:2.7.0:rails:6.0)
rubygem(ruby:2.6.0:fast_gettext) >= 1.4
rubygem(ruby:2.6.0:gettext_i18n_rails) >= 1.8
rubygem(ruby:2.6.0:gettext_i18n_rails_js) >= 1.3
rubygem(ruby:2.6.0:js-routes) >= 1.3.3
rubygem(ruby:2.6.0:kramdown) >= 1.14
rubygem(ruby:2.6.0:puma) >= 3
rubygem(ruby:2.6.0:sass-rails) >= 5.0.1
rubygem(ruby:2.6.0:sprockets) >= 3.7
rubygem(ruby:2.6.0:virtus:1.0) >= 1.0.1
rubygem(ruby:2.7.0:fast_gettext) >= 1.4
rubygem(ruby:2.7.0:gettext_i18n_rails) >= 1.8
rubygem(ruby:2.7.0:gettext_i18n_rails_js) >= 1.3
rubygem(ruby:2.7.0:js-routes) >= 1.3.3
rubygem(ruby:2.7.0:kramdown) >= 1.14
rubygem(ruby:2.7.0:puma) >= 3
rubygem(ruby:2.7.0:sass-rails) >= 5.0.1
rubygem(ruby:2.7.0:sprockets) >= 3.7
rubygem(ruby:2.7.0:virtus:1.0) >= 1.0.1

After this change, we only pull in the distro default ruby version (currently 2.7)