Update CircleCi Node.js version to 10.13

Gatsby has made a breaking change in a minor version so we need to update to avoid the build breaking.

gatsbyjs/gatsby#22400 (comment)

Author: Nick Colley

.circleci/config.yml

@@ -8,7 +8,7 @@ references:
   container_config_node8: &container_config_node8
     working_directory: ~/project/build
     docker:
-      - image: circleci/node:8.16
+      - image: circleci/node:10.13
 
   workspace_root: &workspace_root
     ~/project