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@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
+        uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b # v4
 
       - name: Setup node
         uses: actions/setup-node@7c12f8017d5436eb855f1ed4399f037a36fbd9e8 # v2