Update Build-Release.yml

Author: JanKallman

.github/workflows/Build-Release.yml

@@ -18,7 +18,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: '8.0.x'
+        dotnet-version: '9.0.x'
     - name: Restore dependencies
       run: dotnet restore ./src/EPPlus.sln
     - name: Build