Update Github actions/checkout to v4

The current action is failing as it uses Node 16, which Github has
deprecated.

Author: kjd

.github/workflows/scorecard.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # v3.1.0
+        uses: actions/checkout@v4
         with:
           persist-credentials: false