use node:10.9.0 images on CI

Author: etpinard

.circleci/config.yml

@@ -10,7 +10,7 @@ version: 2.0
 jobs:
   build:
     docker:
-      - image: circleci/node:8.9.4
+      - image: circleci/node:10.9.0
     working_directory: ~/plotly.js
     steps:
       - checkout
@@ -47,7 +47,7 @@ jobs:
   test-jasmine:
     docker:
       # need '-browsers' version to test in real (xvfb-wrapped) browsers
-      - image: circleci/node:8.9.4-browsers
+      - image: circleci/node:10.9.0-browsers
     working_directory: ~/plotly.js
     steps:
       - checkout
@@ -64,7 +64,7 @@ jobs:
   test-jasmine2:
     docker:
       # need '-browsers' version to test in real (xvfb-wrapped) browsers
-      - image: circleci/node:8.9.4-browsers
+      - image: circleci/node:10.9.0-browsers
     working_directory: ~/plotly.js
     steps:
       - checkout
@@ -118,7 +118,7 @@ jobs:
 
   test-syntax:
     docker:
-      - image: circleci/node:8.9.4
+      - image: circleci/node:10.9.0
     working_directory: ~/plotly.js
     steps:
       - checkout