circle: Use Ruby 2.5.1

This _might_ work? Otherwise we can keep 2.4, but upgrade to 2.4.4.

Signed-off-by: Kristofer Rye <[email protected]>

Author: rye

.circleci/config.yml

@@ -27,7 +27,7 @@ x-config:
   x-commands:  # command shorthands
     - &set-ruby-version
       name: Set Ruby Version
-      command: echo "ruby-2.4.2" > ~/.ruby-version
+      command: echo "ruby-2.5.1" > ~/.ruby-version
     - &run-danger
       command: |
         if ! [[ $CIRCLE_PR_NUMBER ]]; then