Chore(deps): Bump peter-evans/dockerhub-description from 3 to 4

Bumps [peter-evans/dockerhub-description](https://github.com/peter-evans/dockerhub-description) from 3 to 4.
- [Release notes](https://github.com/peter-evans/dockerhub-description/releases)
- [Commits](peter-evans/dockerhub-description@v3...v4)

---
updated-dependencies:
- dependency-name: peter-evans/dockerhub-description
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/markdown.yml

@@ -36,7 +36,7 @@ jobs:
         with:
           use-quiet-mode: yes
 
-      - uses: peter-evans/dockerhub-description@v3
+      - uses: peter-evans/dockerhub-description@v4
         if: github.repository == 'qdm12/gluetun' && github.event_name == 'push'
         with:
           username: qmcgaw