Update Node.js to v10.18 (#32)

renovate[bot] · kazupon · commit 63dd1760ca45 · 2019-12-19T11:23:27.000+09:00
diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -7,7 +7,7 @@ executors:
   default:
     docker:
       # specify the version you desire here
-      - image: circleci/node:10.17
+      - image: circleci/node:10.18
 
       # Specify service dependencies here if necessary
       # CircleCI maintains a library of pre-built images
