fix deprecation warning in Rails 5.2
fix deprecation warning in Rails 5.2

Change-Id: I80210b0c486a40168430f9e0cadae29d0780bc3b
Reviewed-on: https://gerrit.instructure.com/159978
Tested-by: Jenkins
Reviewed-by: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>

instructure/canvas-jobs,instructure/inst-jobs,instructure/canvas-jobs,instructure/inst-jobs,instructure/inst-jobs,instructure/canvas-jobs,instructure/inst-jobs,instructure/canvas-jobs