Updated ci-script to target .NET 8.

Author: KristofferStrube

.github/workflows/main.yml

@@ -14,11 +14,11 @@ jobs:
         # Checkout the code
         - uses: actions/checkout@v2
 
-        # Install .NET 7.0 SDK
-        - name: Setup .NET 7 preview
-          uses: actions/setup-dotnet@v1
+        # Install .NET 8.0 SDK
+        - name: Setup .NET 8 preview
+          uses: actions/setup-dotnet@v3
           with:
-            dotnet-version: '7.0.x'
+            dotnet-version: '8.0.x'
             include-prerelease: true
 
         # Generate the website