testBusinessTemplateTwoFileExport: Since 1cbed531, output_encoding was not explicitly set.

This was still working with Zope 2.13 because the default output_encoding for
HTML was iso-8859-15 but this is not the case anymore with Zope 4. Moreover this
should be explicit rather than implicit anyway...
6 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:46:47

passed ERP5.PerformanceTest-Master

00:26:40

failed ERP5.UnitTest-Master

01:30:00

failed ERP5.UnitTest-Master.Medusa

01:31:11

passed SlapOS.Eggs.UnitTest-Master.Python2

00:12:38

passed SlapOS.Eggs.UnitTest-Master.Python3

00:23:44