use checkout v3

Author: adi611

.github/workflows/testslurm.yml

@@ -15,7 +15,7 @@ jobs:
     steps:
     - name: Disable etelemetry
       run: echo "NO_ET=TRUE" >> $GITHUB_ENV
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Pull docker image
       run: |
         docker pull $DOCKER_IMAGE