Bump the bundle CI cache version

Invalidate all previous cache, starting from scratch will be faster
than waiting for all caches to be replaced, which BTW doesn't happen
if a key is already present.

.circleci/config.yml

@@ -46,18 +46,18 @@ commands:
           bundle lock
       - restore_cache:
           keys:
-            - solidus-gems-v2-{{ .Branch }}-{{ checksum "Gemfile.lock" }}
-            - solidus-gems-v2-{{ .Branch }}
-            - solidus-gems-v2-master
-            - solidus-gems-v2
+            - solidus-gems-v3-{{ .Branch }}-{{ checksum "Gemfile.lock" }}
+            - solidus-gems-v3-{{ .Branch }}
+            - solidus-gems-v3-master
+            - solidus-gems-v3
 
       - run: |
           bundle config set path 'vendor/bundle'
           bundle check || bundle install
           bundle clean
 
       - save_cache:
-          key: solidus-gems-v2-{{ .Branch }}-{{ checksum "Gemfile.lock" }}
+          key: solidus-gems-v3-{{ .Branch }}-{{ checksum "Gemfile.lock" }}
           paths:
             - vendor/bundle