Update redis Docker tag to v7

compose.example.yml

@@ -19,7 +19,7 @@ services:
 
   nitter_redis:
     container_name: nitter_redis
-    image: redis:6-alpine
+    image: redis:7-alpine
     command: redis-server --save 60 1 --loglevel warning
     volumes:
     - ./data:/data