chore(deps): update circleci/node:8 docker digest to 64741ba

Author: renovate-bot

.circleci/config.yml

@@ -6,7 +6,7 @@ machine:
 jobs:
   build:
     docker:
-      - image: circleci/node:8@sha256:d44c4c18aebf7b4779192936de39f0dcdedd360f74c511ce77d45a841e2f9803
+      - image: circleci/node:8@sha256:64741baf5e079866de696183e4bfb2d15df032fe365ece06f1cd7f2527eaee03
       - image: mongo:3.7.9@sha256:736eec20a17eafaa988d299902fcaab521cb0ca56af4400f782576afc878d6bc
     environment:
       - NPM_CONFIG_LOGLEVEL: warn