Modernise calls to bundler

Author: mattwynne

.circleci/config.yml

@@ -35,7 +35,8 @@ commands:
       - run:
           name: install dependencies
           command: |
-            bundle install --jobs=4 --retry=3 --path vendor/bundle
+            bundle config set --local path 'vendor/bundle'
+            bundle install
       - save_cache:
           paths:
             - ./vendor/bundle