Fix RSpec/MultipleSubjects cop (#24738)

spec/controllers/api/web/embeds_controller_spec.rb

@@ -10,10 +10,10 @@ describe Api::Web::EmbedsController do
   before { sign_in user }
 
   describe 'POST #create' do
-    subject(:response) { post :create, params: { url: url } }
-
     subject(:body) { JSON.parse(response.body, symbolize_names: true) }
 
+    let(:response) { post :create, params: { url: url } }
+
     context 'when successfully finds status' do
       let(:status) { Fabricate(:status) }
       let(:url) { "http://#{Rails.configuration.x.web_domain}/@#{status.account.username}/#{status.id}" }