Test workflow used new checkout action

.github/workflows/ctest.yaml

@@ -16,7 +16,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
 
     - name: Compiletest
       run: |