Revert "Add a redis cache to gitea"

This reverts commit c0c396f008.

Causes weird stability issues as the process received sig 15 and
restarts, which is strange!

ansible/roles/intersect-docker/files/gitea/docker-compose.yml

@@ -21,12 +21,6 @@ services:
       - /etc/timezone:/etc/timezone:ro
       - /etc/localtime:/etc/localtime:ro
 
-  redis:
-    image: redis:5-alpine
-    restart: unless-stopped
-    volumes:
-      - ./redis:/data
-
   db:
     image: postgres:12-alpine
     restart: unless-stopped