`Update Docker Hub Description` workflow fails in forks

[jsoref]

https://github.com/check-spelling-sandbox/cis-gitlab-benchmark/actions/runs/20715857890/workflow

cis-gitlab-benchmark/.github/workflows/dockerhub-description.yml

Lines 14 to 19 in aaaa22d

	- name: Docker Hub Description
	uses: peter-evans/dockerhub-description@v3
	with:
	username: ${{ secrets.DOCKER_USERNAME }}
	password: ${{ secrets.DOCKER_PASSWORD }}
	repository: logchange/cis-gitlab-benchmark

needs an if guard....

if you don't need to support forks, then if: github.repository_owner == 'logchange' is the simplest.
Otherwise, it'd be something like:

if: env.has_variables
env:
  has_variables: ${{ secrets.DOCKER_USERNAME && secrets.DOCKER_PASSWORD && '1' || '' }}

Otherwise, forks get https://github.com/check-spelling-sandbox/cis-gitlab-benchmark/actions/runs/20715857890/job/59466748506#step:3:5:

Run peter-evans/dockerhub-description@v3
Error: Required input 'username' is missing.