Update default Redis version from 4.0.0 to 6.0.0 for Azure Redis (#2810)

* 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 ([#2810 by philon-msft](https://github.com/StackExchange/StackExchange.Redis/pull/2810))
 
 ## 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

tests/StackExchange.Redis.Tests/ConfigTests.cs

@@ -25,7 +25,7 @@ public class ConfigTests : TestBase
     public ConfigTests(ITestOutputHelper output, SharedConnectionFixture fixture) : base(output, fixture) { }
 
     public Version DefaultVersion = new(3, 0, 0);
-    public Version DefaultAzureVersion = new(4, 0, 0);
+    public Version DefaultAzureVersion = new(6, 0, 0);
 
     [Fact]
     public void ExpectedFields()