fix: fix create project (#867)

* fix: Return ProjectMembershipList for Project

* test: Update test to catch failure

terraso_backend/apps/project_management/models/projects.py

@@ -100,7 +100,7 @@ def save(self, *args, **kwargs):
     @staticmethod
     def create_membership_list() -> MembershipList:
         """Creates a default group for a project"""
-        return MembershipList.objects.create(
+        return ProjectMembershipList.objects.create(
             membership_type=MembershipList.MEMBERSHIP_TYPE_OPEN,
             enroll_method=MembershipList.ENROLL_METHOD_JOIN,
         )

terraso_backend/tests/graphql/mutations/test_projects.py

@@ -18,6 +18,9 @@
             project {
                 id
                 seen
+                membershipList {
+                   id
+                }
             }
         }
     }