chore: roll back redis verison to 7.2.10 because it breaks imap authenticaiton otherwise

Author: ArnC

charts/mailu/values.yaml

@@ -1113,7 +1113,7 @@ redis:
   ## @param redis.architecture Redis architecture. Allowed values: `standalone` or `replication`
   architecture: standalone
   image:
-    tag: 7.4.5
+    tag: 7.2.10
     pullPolicy: IfNotPresent
 
   ## @param redis.auth.enabled DON'T CHANGE THIS VALUE. Mailu doesn't support Redis authentication