Publish to Docker-Hub and Codeberg (#28)

Retry of #27

Reviewed-on: https://codeberg.org/woodpecker-plugins/plugin-docker-buildx/pulls/28
Reviewed-by: qwerty287 <qwerty287@noreply.codeberg.org>
Reviewed-by: Lauris BH <lafriks@noreply.codeberg.org>
Co-authored-by: 6543 <6543@obermui.de>
Co-committed-by: 6543 <6543@obermui.de>

.woodpecker.yml

@@ -13,6 +13,7 @@ pipeline:
 
   publish-dryrun:
     image: woodpeckerci/plugin-docker-buildx:1.0
+    pull: true
     settings:
       platforms: *platforms
       repo: woodpeckerci/plugin-docker-buildx
@@ -26,13 +27,23 @@ pipeline:
     image: woodpeckerci/plugin-docker-buildx:1.0
     settings:
       platforms: *platforms
-      repo: woodpeckerci/plugin-docker-buildx
+      repo: woodpeckerci/plugin-docker-buildx,codeberg.org/woodpecker-plugins/docker-buildx
       auto_tag: true
       dockerfile: Dockerfile.multiarch
+      logins:
+        # Default DockerHub login
+        - registry: https://index.docker.io/v1/
           username:
             from_secret: docker_username
           password:
             from_secret: docker_password
+        # Additional Codeberg login
+        - registry: https://codeberg.org
+          username:
+            from_secret: cb_username
+          password:
+            from_secret: cb_password
+
     when:
       event: [push, tag, cron]
       branch: main