Bump redhat-plumbers-in-action/differential-shellcheck

Bumps [redhat-plumbers-in-action/differential-shellcheck](https://github.com/redhat-plumbers-in-action/differential-shellcheck) from 5.5.5 to 5.5.6.
- [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@0d9e5b2...d965e66)

---
updated-dependencies:
- dependency-name: redhat-plumbers-in-action/differential-shellcheck
  dependency-version: 5.5.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

.github/workflows/differential-shellcheck.yml

@@ -27,7 +27,7 @@ jobs:
 
       - name: Differential ShellCheck
         # yamllint disable-line rule:line-length
-        uses: redhat-plumbers-in-action/differential-shellcheck@0d9e5b29625f871e6a4215380486d6f1a7cb6cdd #@v5.5.5
+        uses: redhat-plumbers-in-action/differential-shellcheck@d965e66ec0b3b2f821f75c8eff9b12442d9a7d1e #@v5.5.6
         with:
           severity: warning
           token: ${{ secrets.GITHUB_TOKEN }}