test: Fix missing model id

Author: ishulgin

src/__tests__/CodexACPAgent/e2e/spawned-agent-fixture.ts

@@ -10,7 +10,7 @@ import type {PermissionResponder} from "./permission-responders";
 import type {LegacyNewSessionResponse} from "../../../AcpExtensions";
 
 export const DEFAULT_TEST_MODEL_ID = ModelId.create("gpt-5.2", "none");
-export const OTHER_TEST_MODEL_ID = ModelId.create("gpt-5.3-codex", "low");
+export const OTHER_TEST_MODEL_ID = ModelId.create("gpt-5.4-mini", "low");
 
 export interface TestSkill {
     readonly name: string;