build(deps): bump redhat-plumbers-in-action/differential-shellcheck

Bumps [redhat-plumbers-in-action/differential-shellcheck](https://github.com/redhat-plumbers-in-action/differential-shellcheck) from 3 to 4.
- [Release notes](https://github.com/redhat-plumbers-in-action/differential-shellcheck/releases)
- [Changelog](https://github.com/redhat-plumbers-in-action/differential-shellcheck/blob/main/docs/CHANGELOG.md)
- [Commits](redhat-plumbers-in-action/differential-shellcheck@v3...v4)

---
updated-dependencies:
- dependency-name: redhat-plumbers-in-action/differential-shellcheck
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/differential-shellcheck.yml

@@ -23,6 +23,6 @@ jobs:
           fetch-depth: 0
 
       - name: Differential ShellCheck
-        uses: redhat-plumbers-in-action/differential-shellcheck@v3
+        uses: redhat-plumbers-in-action/differential-shellcheck@v4
         with:
           token: ${{ secrets.GITHUB_TOKEN }}