Merge pull request #60 from overleaf/update-node-10.21.0

Update node to 10.21.0

services/spelling/.nvmrc

@@ -1 +1 @@
-10.19.0
+10.21.0

services/spelling/Dockerfile

@@ -2,7 +2,7 @@
 # Instead run bin/update_build_scripts from
 # https://github.com/sharelatex/sharelatex-dev-environment
 
-FROM node:10.19.0 as base
+FROM node:10.21.0 as base
 
 WORKDIR /app
 COPY install_deps.sh /app