Change from actions/checkout v3 to v4 to remove node warnings

Signed-off-by: John Mertic <[email protected]>

.github/workflows/validate.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     name: "Validate landscape.yml file"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: cncf/landscape2-validate-action@v2
         with:
           target_kind: data