Remove is_a?(Hash) from unless params[:variables] in create_pipeline_variables

app/services/ci/pipeline_trigger_service.rb

@@ -32,7 +32,7 @@ module Ci
     end
 
     def create_pipeline_variables!(pipeline)
-      return unless params[:variables].is_a?(Hash)
+      return unless params[:variables]
 
       variables = params[:variables].map do |key, value|
         { key: key, value: value }