Convert issuable type to symbol before comparing

- The issuable type argument can be a string so it
shouldn't be compare with a symbol before
converting it first

ee/app/workers/ee/issuable_export_csv_worker.rb

@@ -11,7 +11,7 @@ module EE
 
     override :export_service
     def export_service(type, user, project, params)
-      return super unless type == :requirement
+      return super unless type.to_sym == :requirement
 
       fields = params.with_indifferent_access.delete(:selected_fields) || []
       issuable_classes = issuable_classes_for(type.to_sym)
@@ -21,7 +21,7 @@ module EE
 
     override :issuable_classes_for
     def issuable_classes_for(type)
-      return super unless type == :requirement
+      return super unless type.to_sym == :requirement
 
       { finder: ::RequirementsManagement::RequirementsFinder, service: ::RequirementsManagement::ExportCsvService }
     end

ee/spec/workers/ee/issuable_export_csv_worker_spec.rb

@@ -10,7 +10,7 @@ RSpec.describe IssuableExportCsvWorker do
   subject { described_class.new.perform(issuable_type, user.id, project.id, params) }
 
   context 'when issuable type is :requirement' do
-    let(:issuable_type) { :requirement }
+    let(:issuable_type) { 'requirement' }
 
     it 'emails a CSV' do
       expect { subject }.to change(ActionMailer::Base.deliveries, :size).by(1)