style(cloudwatch-mcp-server): fix ruff format extra blank line in test

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mtmtcode

src/cloudwatch-mcp-server/tests/cloudwatch_logs/test_logs_models.py

@@ -40,7 +40,6 @@ def test_convert_to_iso8601_returns_string_unchanged(self):
         # Verify the string timestamp was returned unchanged
         assert log_group.creationTime == '2023-01-01T00:00:00+00:00'
 
-
     def test_stored_bytes_optional(self):
         """Test that storedBytes is optional since AWS API may omit it."""
         log_group_data = {