unit test error on my computer

[splasky]

When running pytest in unit_test, the dttm_sql_literal test fails on my machine. I checked the test report and found that both epoch_s and epoch_ms tests are reporting errors. This appears to be due to my local timezone being applied, causing the timestamp to be offset by +8 hours.

I attempted to fix this with the following commit: splasky@efdb982. However, I'm unsure if this addresses the underlying cause. Could you please review it? Thanks.