Update tests.yml

Author: JunaMeinhold

.github/workflows/tests.yml

@@ -14,12 +14,12 @@ jobs:
 
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Setup .NET
-      uses: actions/setup-dotnet@v3
+      uses: actions/setup-dotnet@v4
       with:
-        dotnet-version: '8.x'
+        dotnet-version: '9.x'
 
     - name: Restore dependencies
       run: dotnet restore