Use #query_scope instead of #parent in a Spinach feature

Signed-off-by: Rémy Coutable <remy@rymai.me>

features/steps/project/commits/commits.rb

@@ -62,7 +62,7 @@ class Spinach::Features::ProjectCommits < Spinach::FeatureSteps
   end
 
   step 'I should see additional file lines' do
-    page.within @diff.parent do
+    page.within @diff.query_scope do
       expect(first('.new_line').text).not_to have_content "..."
     end
   end