Add setup for .NET 9.0 in build workflow

Author: Perksey

.github/workflows/build.yml

@@ -47,6 +47,10 @@ jobs:
       uses: actions/setup-dotnet@v1
       with:
         dotnet-version: 7.0.102
+    - name: Setup .NET 9.0
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 9.0.305
     - name: Install Workloads
       run: dotnet workload install android ios maccatalyst
     - name: Test