update build pipeline to net 9

Author: JoshLozensky

.github/workflows/dotnet.yml

@@ -19,6 +19,6 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v3
       with:
-        dotnet-version: 7.x
+        dotnet-version: 9.x
     - name: Build
       run: dotnet build  buildAllSlns.proj