Remove unused imports flagged by ruff

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

Author: Jeomon

operator_use/acp/server.py

@@ -34,7 +34,6 @@
 from operator_use.acp.config import ACPServerConfig
 from operator_use.acp.provenance import ACPProvenance, fetch_public_key
 from operator_use.acp.models import (
-    AgentCapabilities,
     AgentListResponse,
     AgentMetadata,
     MessagePart,

tests/test_acp_server.py

@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 import asyncio
-import json
 import pytest
 import pytest_asyncio
 from aiohttp.test_utils import TestClient, TestServer