Use 8.0.x in publish-nuget.yaml

Author: danielmarbach

.github/workflows/publish-nuget.yaml

@@ -13,6 +13,11 @@ jobs:
       - uses: actions/checkout@v4
         with:
           submodules: true
+      - name: Setup .NET SDK
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: |
+            8.0.x          
       - uses: actions/cache@v4
         with:
           path: |