Uses the frozen_string_literal magic comment (will be the default in Ruby 3)

spec/app/models/interesting_finding_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 describe WPScan::Model::InterestingFinding do
   it_behaves_like WPScan::References do
     subject(:finding) { described_class.new('http://e.org/file.php', opts) }