bump byebug

Change-Id: I055356d527f06e04d50ac713e06466493e42c37b
Reviewed-on: https://gerrit.instructure.com/43958
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>