upgrade aws-sdk gem to 1.52.0

we are seeing errors stream data from aws, when passing a block to read, which
appears tomatches this bug: https://github.com/aws/aws-sdk-ruby/issues/557. at
the time of this commit, it appears that upgrading the gem increases stability,
although it sounds like it is not a total solution yet, especially for ruby 2.

closes CNVS-15441

test plan:
- make sure file uploads to s3 still work

Change-Id: Ib2e84bc4697583337c1ad03da4677913a2a78aad
Reviewed-on: https://gerrit.instructure.com/40937
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>