Sass 3.7.3 compatibility

[pvalena]

When executing test suite with Sass 3.7.3, it fails with:

lib/compass/core/sass_extensions/functions/urls.rb:5:in `has?': undefined method `has?' for Sass::Util:Module (NoMethodError)

[pvalena]

As you can see in Fedora, where tests are executed after a buildd, here:
https://copr-be.cloud.fedoraproject.org/results/pvalena/ruby26-gems/fedora-rawhide-x86_64/00846756-rubygem-compass-core/build.log.gz

[sooendre]

As you can see in Fedora, where tests are executed after a buildd, here:
https://copr-be.cloud.fedoraproject.org/results/pvalena/ruby26-gems/fedora-rawhide-x86_64/00846756-rubygem-compass-core/build.log.gz

classic, 404