Fix appraisal for Rails 6
Fix appraisal for Rails 6

Change-Id: Ic3e5d674ae60465d8e310be28577b677a2d7e513
Reviewed-on: https://gerrit.instructure.com/210479
Tested-by: Jenkins
Reviewed-by: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

instructure/switchman,instructure/switchman