🐛(backend) add partial_update action to the abilities

partial_update action was missing for the permission.
So when we were patching the template,
it was not working.
This commit adds the partial_update action
to the abilities.

src/backend/core/tests/templates/test_api_templates_retrieve.py

@@ -22,6 +22,7 @@ def test_api_templates_retrieve_anonymous_public():
             "destroy": False,
             "generate_document": True,
             "manage_accesses": False,
+            "partial_update": False,
             "retrieve": True,
             "update": False,
         },
@@ -63,6 +64,7 @@ def test_api_templates_retrieve_authenticated_unrelated_public():
             "destroy": False,
             "generate_document": True,
             "manage_accesses": False,
+            "partial_update": False,
             "retrieve": True,
             "update": False,
         },