Update .NET SDK in CI build

Author: commonsensesoftware

build/steps-ci.yml

@@ -11,7 +11,7 @@ steps:
   displayName: Install .NET SDK
   inputs:
     packageType: sdk
-    version: 7.0.x # https://github.com/dotnet/core/blob/main/release-notes/releases-index.json
+    version: 8.0.x # https://github.com/dotnet/core/blob/main/release-notes/releases-index.json
 
 - task: DotNetCoreCLI@2
   displayName: Build and Test