chore(deps): update node:8.16.0 docker digest to 4d7a035

Author: renovate-bot

.circleci/config.yml

@@ -6,7 +6,7 @@ machine:
 jobs:
   build:
     docker:
-      - image: node:8.16.0@sha256:39ed5b5d194692727e785327790d0dbc5bc4bcfa041c93635d5bcc56bd6dbb5f
+      - image: node:8.16.0@sha256:4d7a0358ce961c70514ac6e65a57cbeda3a143faba5da3fec22e62262f6448b0
     environment:
       - NPM_CONFIG_LOGLEVEL: warn
     working_directory: ~/repo