build(woodpecker): build docker image on push to next

.woodpecker/push-next.yml

@@ -11,3 +11,16 @@ steps:
       repository_token: "776a3b928b852472c2af727a360c85c00af64b9f"
       prefix_regex: "(#|//) (TODO|FIXME): "
       debug: false
+
+  docker-build:
+    when:
+      - event: push
+        branch: next
+    # INFO: https://woodpecker-ci.org/plugins/Docker%20Buildx
+    image: docker.io/woodpeckerci/plugin-docker-buildx:4.2.0
+    settings:
+      username: kemitix
+      repo: git.kemitix.net/kemitix/git-next
+      dockerfile: Dockerfile
+      auto_tag: false
+      dry-run: true # don't push to remote repo