ci: use 2.1 version of circleci config

Author: vladholubiev

.circleci/config.yml

@@ -1,24 +1,28 @@
-version: 2
-
-jobs:
-  build:
+executors:
+  node8:
     docker:
       - image: circleci/node:8
-
     working_directory: ~/repo
 
+version: 2.1
+
+jobs:
+  build:
+    executor: node8
     steps:
       - checkout
+
       - restore_cache:
           keys:
-          - v1-dependencies-{{ checksum "package.json" }}
-          - v1-dependencies-
+            - v1-dependencies-{{ checksum "package.json" }}
+            - v1-dependencies-
 
       - run: yarn
-      - run: yarn test
 
       - save_cache:
           paths:
             - node_modules
             - yarn.lock
           key: v1-dependencies-{{ checksum "package.json" }}
+
+      - run: yarn test