release 8.x -> 9.x

Author: ikpil

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Setup Dotnet
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '8.x'
+          dotnet-version: '9.x'
 
       - name: restore dependencies
         run: dotnet restore