Bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/container-tests.yml

@@ -21,7 +21,7 @@ jobs:
       && contains(fromJson('["OWNER", "MEMBER"]'), github.event.comment.author_association)
     steps:
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           ref: "refs/pull/${{ github.event.issue.number }}/head"
 

.github/workflows/differential-shellcheck.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Repository checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
 

.github/workflows/sanity-tests.yaml

@@ -21,7 +21,7 @@ jobs:
           echo "PR_NR=${PR_URL##*/}" >> $GITHUB_OUTPUT
 
       - name: Checkout repo
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           ref: "refs/pull/${{ steps.pr_nr.outputs.PR_NR }}/head"