Skip char_group tokenizer and field aliases on <6.4.0

Author: russcam

src/Tests/Tests/Analysis/Tokenizers/TokenizerTests.cs

@@ -219,8 +219,9 @@ public class NoriTests : TokenizerAssertionBase<NoriTests>
 			);
 
 			public override object Json => new {type = "nori_tokenizer", decompound_mode = "mixed"};
-    }
+		}
 
+		[SkipVersion("<6.4.0", "char_group introduced in 6.4.0")]
 		public class CharGroupTests : TokenizerAssertionBase<CharGroupTests>
 		{
 			private readonly string[] _chars = {"whitespace", "-", "\n"};

src/Tests/Tests/Mapping/Types/Specialized/FieldAlias/FieldAliasPropertyTests.cs

@@ -1,4 +1,5 @@
 using System;
+using Elastic.Xunit.XunitPlumbing;
 using Nest;
 using Tests.Core.ManagedElasticsearch.Clusters;
 using Tests.Core.ManagedElasticsearch.NodeSeeders;
@@ -7,6 +8,7 @@
 
 namespace Tests.Mapping.Types.Specialized.FieldAlias
 {
+	[SkipVersion("<6.4.0", "field aliases introduced in 6.4.0")]
 	public class FieldAliasPropertyTests : PropertyTestsBase
 	{
 		public FieldAliasPropertyTests(WritableCluster cluster, EndpointUsage usage) : base(cluster, usage) { }