Improve GitHub Actions workflow

Author: andyone

.github/workflows/ci.yml

@@ -56,6 +56,12 @@ jobs:
       - name: Code checkout
         uses: actions/checkout@v2
 
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Run Perfecto docker image
         uses: docker://essentialkaos/perfecto:slim
         with: