Update default Redis version from 4.0.0 to 6.0.0 for Azure Redis resources

Author: philon-msft

docs/ReleaseNotes.md

@@ -8,7 +8,7 @@ Current package versions:
 
 ## Unreleased
 
-No pending unreleased changes.
+- Update default Redis version from 4.0.0 to 6.0.0 for Azure Redis resources
 
 ## 2.8.16
 

src/StackExchange.Redis/Configuration/AzureOptionsProvider.cs

@@ -16,9 +16,9 @@ public class AzureOptionsProvider : DefaultOptionsProvider
         public override bool AbortOnConnectFail => false;
 
         /// <summary>
-        /// The minimum version of Redis in Azure is 4, so use the widest set of available commands when connecting.
+        /// The minimum version of Redis in Azure is 6, so use the widest set of available commands when connecting.
         /// </summary>
-        public override Version DefaultVersion => RedisFeatures.v4_0_0;
+        public override Version DefaultVersion => RedisFeatures.v6_0_0;
 
         /// <summary>
         /// List of domains known to be Azure Redis, so we can light up some helpful functionality