spec: change expected error

Author: gildesmarais

spec/routes/auto_source_spec.rb

@@ -94,7 +94,7 @@ def app = described_class
 
       it 'responds with Error', :aggregate_failures do
         expect(response.status).to eq 422
-        expect(response.body).to match(/Html2rss::Config::InvalidConfig/)
+        expect(response.body).to match(/Html2rss::RequestService::UnknownStrategy/)
       end
     end
   end