fix sharding skip for rspec 3

fixes CNVS-16812

Change-Id: If638a2cc3d9a72746af5b66fa86411a5e7b0c22b
Reviewed-on: https://gerrit.instructure.com/44200
Product-Review: Rob Orton <rob@instructure.com>
Reviewed-by: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
Reviewed-by: Bryan Madsen <bryan@instructure.com>
QA-Review: Bryan Madsen <bryan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>