Update actions/checkout action to v4

Update actions/checkout from 2 to 4

Change-type: patch

Author: balena-renovate[bot]

.github/workflows/publish-docs.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out
-        uses: actions/checkout@v2
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
       - name: Setup node
         uses: actions/setup-node@v2