FIX: Force string conversions to UTF-8 "bytes" (#11315)

https://meta.discourse.org/t/cant-create-poll-with-some-chinese-options/170836

plugins/poll/spec/controllers/posts_controller_spec.rb

@@ -71,6 +71,16 @@ describe PostsController do
       expect(json["errors"][0]).to eq(I18n.t("poll.default_poll_must_have_different_options"))
     end
 
+    it "accepts different Chinese options" do
+      SiteSetting.default_locale = 'zh_CN'
+
+      post :create, params: {
+        title: title, raw: "[poll]\n- Microsoft Edge（新）\n- Microsoft Edge（旧）\n[/poll]"
+      }, format: :json
+
+      expect(response).to be_successful
+    end
+
     it "should have at least 1 options" do
       post :create, params: {
         title: title, raw: "[poll]\n[/poll]"