chore(deps): update node:8.16.0 docker digest to 957cab2

Author: renovate-bot

.circleci/config.yml

@@ -6,7 +6,7 @@ machine:
 jobs:
   build:
     docker:
-      - image: node:8.16.0@sha256:9f1271db6874a0570e00f39273003ff22c1d358c0c612f553c11c8727ce49426
+      - image: node:8.16.0@sha256:957cab2653bde49d195e0a98c6ae0c1700ed51eb94fce30faadaceacf331a0a1
     environment:
       - NPM_CONFIG_LOGLEVEL: warn
     working_directory: ~/repo