Re-add property to project_attributes.yml

This change re-adds a property to `project_attributes.yml` to fix a
broken master.

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/79968#note_842371207
https://gitlab.com/gitlab-org/gitlab/-/issues/352764

spec/requests/api/project_attributes.yml

@@ -121,6 +121,7 @@ project_feature:
     - created_at
     - metrics_dashboard_access_level
     - project_id
+    - requirements_access_level
     - security_and_compliance_access_level
     - updated_at
   computed_attributes: