docker: always tag latest release with latest

The master branch isn't build each time, instead the latest release
should be tagged with `latest` so `docker run aparcar/asu` actually run
the latest release.

Signed-off-by: Paul Spooren <mail@aparcar.org>

Author: aparcar

.github/workflows/publish.yml

@@ -41,6 +41,7 @@ jobs:
         password: ${{ secrets.DOCKER_PASSWORD }}
         repository: aparcar/asu
         tag_with_ref: true
+        tags: latest
 
     - name: Image digest
       run: echo ${{ steps.docker_build.outputs.digest }}