bump redis to 4.1.3

https://github.com/redis/redis-rb/blob/master/CHANGELOG.md

Change-Id: I156b01c2e947beace29b1e6f3dc026144fd927fc
Reviewed-on: https://gerrit.instructure.com/212647
Tested-by: Jenkins
QA-Review: Simon Williams <simon@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>

Gemfile.d/redis.rb

@@ -16,7 +16,7 @@
 # with this program. If not, see <http://www.gnu.org/licenses/>.
 
 group :redis do
-  gem 'redis', '4.0.1'
+  gem 'redis', '4.1.3'
   gem 'redis-scripting', '1.0.1'
 
   gem 'digest-murmurhash', '1.1.1'