test(static_controller): fix inconsistency with Settings merge

spec/controllers/static_controller_spec.rb

@@ -26,17 +26,24 @@ RSpec.describe StaticController, type: :controller do
       end
     end
 
-    it 'setup github' do
-      Settings[:ccs] = {
+    describe 'github' do
+      before (:each) do
+        Settings.merge!(
+          ccs: {
             ccs_method: 'github',
             options: {
               account: 'account',
               repo: 'repo'
             }
           }
+        )
+      end
+
+      it 'setup github' do
         expect(File).to receive(:read).with("#{Rails.root}/CCS_HASH").and_return("hash\n")
         get('ccs')
         expect(response).to redirect_to 'https://github.com/account/repo/tree/hash'
       end
     end
   end
+end