fix: mock prisma find_unique as AsyncMock in get_agent_by_id test

The endpoint now refreshes agent spend from DB when found in registry,
so the test must provide an AsyncMock for the awaited find_unique call.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_litellm/proxy/agent_endpoints/test_endpoints.py

@@ -295,6 +295,9 @@ class TestAgentRBACInternalUser:
             return_value=_sample_agent_response()
         )
         with patch("litellm.proxy.proxy_server.prisma_client") as mock_prisma:
+            mock_prisma.db.litellm_agentstable.find_unique = AsyncMock(
+                return_value=MagicMock(spend=0.0)
+            )
             resp = self.internal_client.get(
                 "/v1/agents/agent-123", headers={"Authorization": "Bearer k"}
             )