ci: use actions/checkout@v4

Use actions/checkout@v4 when checking out the example-application
repository in CI. The new version uses Node20 instead of the
deprecated Node16.

Signed-off-by: Henrik Brix Andersen <[email protected]>

Author: henrikbrixandersen

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           path: example-application