updated checkout action

Author: patrick-werner

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
       - name: Checkout code
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       # Java and .NET are already installed on ubuntu-latest