Update github actions to latest versions of 4.x + .NET 9.0

Author: mjebrahimi

.github/workflows/dotnetcore.yml

@@ -17,12 +17,12 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v4.1.1
+      uses: actions/checkout@v4
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v4.0.0
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: 8.x.x
+        dotnet-version: 9.x.x
 
     - name: Restore dependencies
       run: dotnet restore