Update redis Docker tag to v7

| datasource | package | from | to |
| ---------- | ------- | ---- | -- |
| docker     | redis   | 3    | 7  |


Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Diff for: redis-demo/docker-compose.yml

@@ -6,13 +6,13 @@ nginxplus:
   - "8080:8080"
 
 redis-master:
-  image: redis:3
+  image: redis:7
   container_name: redis-master
   ports:
   - "63791:6379"
 
 redis-slave1:
-  image: redis:3
+  image: redis:7
   command: redis-server --slaveof redis-master 6379
   container_name: redis-slave1
   links:
@@ -21,7 +21,7 @@ redis-slave1:
   - "63792:6379"
 
 redis-slave2:
-  image: redis:3
+  image: redis:7
   command: redis-server --slaveof redis-master 6379
   container_name: redis-slave2
   links:

Diff for: redis-demo/sentinel/Dockerfile

@@ -1,4 +1,4 @@
-FROM redis:3
+FROM redis:7
 
 MAINTAINER Kunal Pariani <[email protected]>