[spec] dotnet 9.0.x set

Author: i4004

.github/workflows/build.yml

@@ -19,7 +19,9 @@ jobs:
         uses: actions/[email protected]
 
       - name: Install DotNet
-        uses: actions/[email protected]
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: "9.0.x"
 
       - name: Restore Dependencies
         run: dotnet restore