ci: fix dockerhub-login declaration

Author: hleb-rubanau

.github/actions/dockerhub-login/action.yml

@@ -1,7 +1,9 @@
 name: login to Dockerhub  (to prevent image trottling)
 runs:
-  - name: docker login
-    run: bash -ce 'echo "$DOCKERHUB_PASSWORD" | docker login -u "$DOCKERHUB_USERNAME" --password-stdin'
-    env:
-      DOCKERHUB_PASSWORD: {{ secrets.DOCKERHUB_PASSWORD }}
-      DOCKERHUB_USERNAME: {{ secrets.DOCKERHUB_USERNAME }}
+  using: composite
+  steps:
+    - name: docker login
+      run: bash -ce 'echo "$DOCKERHUB_PASSWORD" | docker login -u "$DOCKERHUB_USERNAME" --password-stdin'
+      env:
+        DOCKERHUB_PASSWORD: {{ secrets.DOCKERHUB_PASSWORD }}
+        DOCKERHUB_USERNAME: {{ secrets.DOCKERHUB_USERNAME }}