fix(tests): gate test_mcp_oauth_metadata on the MCP SDK

The module hard-imported mcp.shared.auth and errored at collection on a
default install; importorskip it like test_mcp_oauth_missing_iss.py.

tests/tools/test_mcp_oauth_metadata.py

@@ -24,7 +24,9 @@ from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
-from mcp.shared.auth import OAuthMetadata
+pytest.importorskip("mcp.shared.auth", reason="MCP SDK not installed")
+
+from mcp.shared.auth import OAuthMetadata  # noqa: E402
 
 from tools.mcp_oauth import HermesTokenStorage
 from tools.mcp_oauth_manager import _HERMES_PROVIDER_CLS