fix: Remove unused import, fix mock_cache fixture for 2.0 settings

- Remove unused `from typing import Callable` in connection.py (lint failure)
- Update mock_cache fixture: `cache` → `download_path` (KeyError in test_attach)

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

Author: dimitri-yatsenko

src/datajoint/connection.py

@@ -11,7 +11,6 @@
 import re
 import warnings
 from contextlib import contextmanager
-from typing import Callable
 
 from . import errors
 from .adapters import get_adapter

tests/conftest.py

@@ -536,13 +536,13 @@ def mock_stores(stores_config):
 
 @pytest.fixture
 def mock_cache(tmpdir_factory):
-    og_cache = dj.config.get("cache")
-    dj.config["cache"] = tmpdir_factory.mktemp("cache")
+    og_cache = dj.config.get("download_path")
+    dj.config["download_path"] = str(tmpdir_factory.mktemp("cache"))
     yield
     if og_cache is None:
-        del dj.config["cache"]
+        del dj.config["download_path"]
     else:
-        dj.config["cache"] = og_cache
+        dj.config["download_path"] = og_cache
 
 
 @pytest.fixture(scope="session")