update TwitchLib.EventSub.Core to v2.6

Author: AoshiW

TwitchLib.EventSub.Websockets/TwitchLib.EventSub.Websockets.csproj

@@ -31,7 +31,7 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Logging" Version="8.0.0" />
-    <PackageReference Include="TwitchLib.EventSub.Core" Version="2.5.3-preview-e4631fd" />
+    <PackageReference Include="TwitchLib.EventSub.Core" Version="2.6.0" />
 	  <PackageReference Include="System.Text.Json" Version="8.0.5" />
   </ItemGroup>