fix: replace unsupported gpt-5.1-codex-mini model in github-remote-mcp-auth-test (#28321)

Author: Copilot

.github/workflows/github-remote-mcp-auth-test.lock.yml

@@ -9,7 +9,7 @@ permissions:
   discussions: read
 engine:
   id: copilot
-  model: gpt-5.1-codex-mini
+  model: gpt-5.4-mini
 tools:
   mount-as-clis: true
   github: