fix: restore required pytest and Path imports in test_config

Tests use pytest.raises and Path, so these imports must be kept.
Only removed unused json import.

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

Author: drernie

deploy/tests/test_config.py

@@ -1,6 +1,8 @@
 """Tests for configuration management."""
 
-import json
+from pathlib import Path
+
+import pytest
 
 from lib.config import DeploymentConfig