Update to use dotnet 8

Author: cameronwhite

.github/workflows/deploy.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v3
         with:
-          dotnet-version: 7.0.x
+          dotnet-version: 8.0.x
       - name: Install mautil
         run: dotnet tool install --global Mono.Addins.UtilTool
       - name: Generate add-in repository