ci: publish docker image after new release

Closes reanahub/reana#752

.github/workflows/release-docker.yml

@@ -0,0 +1,23 @@
+# This file is part of REANA.
+# Copyright (C) 2023 CERN.
+#
+# REANA is free software; you can redistribute it and/or modify it
+# under the terms of the MIT License; see LICENSE file for more details.
+
+name: release-docker
+
+on:
+  push:
+    tags:
+      - "*"
+
+jobs:
+  release-docker:
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Release docker image
+        uses: reanahub/reana-github-actions/release-docker@v1
+        with:
+          username: ${{ secrets.DOCKER_USER }}
+          token: ${{ secrets.DOCKER_TOKEN }}
+          organisation: ${{ secrets.DOCKER_ORGANISATION }}