erp5_base: Fix typo: OpenOrder is actually in erp5_open_trade (937500a1).

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passed ERP5.CodingStyleTest-Master

01:49:04

passed ERP5.PerformanceTest-Master

00:32:17

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02:07:42

passed SlapOS.Eggs.UnitTest-Master.Python2

00:17:36

passed SlapOS.Eggs.UnitTest-Master.Python3

00:19:12