pages workflow: downgrade to .net 9

Author: Jani Giannoudis

.github/workflows/pages.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: '10.0.x'
+          dotnet-version: '9.0.x'
 
       - name: Configure GitHub Packages source
         run: |