chore(proxy): regenerate lazy OpenAPI snapshot for is_error field

The ChatCompletionToolMessage schema gained the litellm-internal
is_error carrier; regenerate the snapshot so Check UI API Types
stays green.

Generated-by: GLM-5.3-Flash (ZCode)

litellm/proxy/_lazy_openapi_snapshot.json

@@ -44020,6 +44020,10 @@
               ],
               "title": "Content"
             },
+            "is_error": {
+              "title": "Is Error",
+              "type": "boolean"
+            },
             "role": {
               "const": "tool",
               "title": "Role",