More accurate TIF filtering based on snapshot timestamp instead of current time.

[sean-thorburn]

Filtering for expired orders based on the current time can filter out orders that may not have expired at the time that the snapshot was taken. Instead of filtering by the current time, you can filter by the last update to the book snapshot.

[hoakbuilds]

This looks good to me, you make a great point on snapshot timestamp instead of current time.

Could you fix the test to take into account these changes and bump version to 6.0.3.4 so that the pipeline takes care of the rest?

[coveralls]

Pull Request Test Coverage Report for Build 1939235874

• 19 of 19 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 80.414%

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Totals
Change from base Build 1935115420:	-0.02%
Covered Lines:	2424
Relevant Lines:	2971

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💛 - Coveralls