Update the README

Author: jsakamoto

Readme.md

@@ -64,8 +64,8 @@ private async void QueryByDomain()
 
 WhoisClient.NET version | Supported Framework
 ------------------------|--------------------
-5.x                     | .NET 5, 6, 7, 8 or later, .NET Standard 2.0 (including .NET Core 2.0 or later, .NET Framework 4.6.2 or later)
-4.x                     | .NET 5, 6, 7, 8 or later, .NET Standard 2.0 (including .NET Core 2.0 or later, .NET Framework 4.6.2 or later)
+5.x                     | .NET 5, 6, 7, 8, 9 or later, .NET Standard 2.0 (including .NET Core 2.0 or later, .NET Framework 4.6.2 or later)
+4.x                     | .NET 5, 6, 7, 8, 9 or later, .NET Standard 2.0 (including .NET Core 2.0 or later, .NET Framework 4.6.2 or later)
 3.x                     | .NET Standard 1.4 (including .NET Core 1.1 or later, .NET Framework 4.5 or later)
 2.x                     | .NET Framework 4.0 or later
 1.x                     | .NET Framework 4.0 or later