Bump circleci xcode environment to 12.1.0

Author: ldiqual

.circleci/config.yml

@@ -1,12 +1,12 @@
 
 # Shared Xcode version between jobs
-xcode-version: &xcode-version "11.3.1"
+xcode-version: &xcode-version "12.0.1"
 
 # This is the key that we use to store and restore our dependencies cache.
 # It needs to be different anytime we add Pods, Gems, or npm packages.
 # If something went wrong during a cache build, you can increase the cache version
 # like this: 1-dependencies-... => 2-dependencies-...
-cache-key: &cache-key 3-dependencies-{{ checksum "Gemfile.lock" }}-{{ checksum "Podfile.lock" }}
+cache-key: &cache-key 4-dependencies-{{ checksum "Gemfile.lock" }}-{{ checksum "Podfile.lock" }}
 
 # Environment that is shared between jobs
 shared-env: &shared-env
@@ -25,6 +25,9 @@ jobs:
       - checkout
       - restore_cache:
           key: *cache-key
+      - run:
+          name: Install bundler
+          command: gem install bundler:1.17.3
       - run:
           name: Install Ruby bundle dependencies
           command: bundle check || bundle install