fix: Don't set contractperiod_startdate and contractperiod_enddate to tuples

[jpmckinney]

fixes #319

[coveralls]

Pull Request Test Coverage Report for Build 10333445629

Details

• 5 of 9 (55.56%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.03%) to 86.42%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
app/sources/colombia.py	5	9	55.56%
<!--	Total:	5	9	55.56%	-->

Totals
Change from base Build 10333434104:	-0.03%
Covered Lines:	2030
Relevant Lines:	2349

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💛 - Coveralls