update react on rails version in tests

Author: AbanoubGhadban

spec/dummy/spec/helpers/react_on_rails_pro_helper_spec.rb

@@ -200,7 +200,7 @@ def response; end
     end
     let(:rails_context_tag) do
       <<-SCRIPT.strip_heredoc
-        <script type="application/json" id="js-react-on-rails-context">{"railsEnv":"test","inMailer":false,"i18nLocale":"en","i18nDefaultLocale":"en","rorVersion":"14.0.5","rorPro":true,"rorProVersion":"4.0.0.rc.5","href":"http://foobar.com/development","location":"/development","scheme":"http","host":"foobar.com","port":null,"pathname":"/development","search":null,"httpAcceptLanguage":"en","somethingUseful":null,"serverSide":false}</script>
+        <script type="application/json" id="js-react-on-rails-context">{"railsEnv":"test","inMailer":false,"i18nLocale":"en","i18nDefaultLocale":"en","rorVersion":"15.0.0.alpha.1","rorPro":true,"rorProVersion":"4.0.0.rc.5","href":"http://foobar.com/development","location":"/development","scheme":"http","host":"foobar.com","port":null,"pathname":"/development","search":null,"httpAcceptLanguage":"en","somethingUseful":null,"serverSide":false}</script>
       SCRIPT
     end
     let(:react_component_div_with_initial_chunk) do