Upgrade .NET version to 8.0.x in GitHub workflows

Updated the .NET version from 7.0.x to 8.0.x in both the CI and publish workflows. This ensures compatibility with the latest .NET features and keeps the project up-to-date. Adjusted configurations to reflect this change while maintaining existing functionality.

Author: magahl-swegon

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v2
       with:
-        dotnet-version: 7.0.x
+        dotnet-version: 8.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Build

.github/workflows/publish.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v2
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: 8.0.x
 
       - uses: dotnet/nbgv@master
         id: nbgv