Fix test_monthly_moy_execution_is_not_due

Received a mail from Travis, here is a fix

Force utc in test_monthly_moy_execution_is_not_due

Its appear there is some strange behaviour with
the localtime. There is an offset of 3600 on
some timezone, (on GMT+xx but not on GMT-xx),
furthermore, some GMT+xx works without the offset,
like Puerto Rico.