Remove parameterise deprecation warning

DEPRECATION WARNING: Passing the separator argument as a positional
parameter is deprecated and will soon be removed. Use `separator: '_'`
instead.

spec/shared/features/relationable.rb

@@ -1,6 +1,6 @@
 shared_examples "relationable" do |relationable_model_name|
 
-  let(:relationable) { create(relationable_model_name.name.parameterize("_").to_sym) }
+  let(:relationable) { create(relationable_model_name.name.parameterize(separator: "_").to_sym) }
   let(:related1) { create([:proposal, :debate, :budget_investment].sample) }
   let(:related2) { create([:proposal, :debate, :budget_investment].sample) }
   let(:user) { create(:user) }