[misc] cleanup unused dependency on redis

services/spelling/buildscript.txt

@@ -4,7 +4,7 @@ spelling
 --env-add=
 --node-version=10.19.0
 --acceptance-creds=None
---dependencies=mongo,redis
+--dependencies=mongo
 --docker-repos=gcr.io/overleaf-ops
 --env-pass-through=
 --data-dirs=cache

services/spelling/docker-compose.ci.yml

@@ -27,8 +27,6 @@ services:
     depends_on:
       mongo:
         condition: service_healthy
-      redis:
-        condition: service_healthy
     user: node
     command: npm run test:acceptance:_run
 
@@ -40,8 +38,5 @@ services:
       - ./:/tmp/build/
     command: tar -czf /tmp/build/build.tar.gz --exclude=build.tar.gz --exclude-vcs .
     user: root
-  redis:
-    image: redis
-
   mongo:
     image: mongo:3.6

services/spelling/docker-compose.yml

@@ -38,13 +38,8 @@ services:
     depends_on:
       mongo:
         condition: service_healthy
-      redis:
-        condition: service_healthy
     command: npm run test:acceptance
 
-  redis:
-    image: redis
-
   mongo:
     image: mongo:3.6