Updates .NET SDK to version 8.x

Author: neoscie

.github/workflows/dotnet-publish.yml

@@ -10,7 +10,7 @@ on:
 env:
   ARTIFACTS_FEED_URL: https://api.nuget.org/v3/index.json
   BUILD_CONFIGURATION: "Release"
-  DOTNET_VERSION: "6.x"
+  DOTNET_VERSION: "8.x"
 
 jobs:
   build-and-deploy: