[fix] CI: use Node 10

.gitlab-ci.yml

@@ -46,6 +46,8 @@ push_to_github:
   before_script:
     - export NVM_DIR="$HOME/.nvm"
     - . "$NVM_DIR/nvm.sh"
+    - nvm install 10
+    - nvm use 10
 
 .cached_nvm: &cached_nvm
   <<: *nvm_env