feat: add woodpecker pipeline

.woodpecker/build.yml

@@ -0,0 +1,42 @@
+---
+
+when:
+    branch: main
+    path:
+        - Dockerfile
+        - .woodpecker/build.yml
+
+variables:
+  - &buildx woodpeckerci/plugin-docker-buildx:4.2.0
+  - &buildx_settings
+    platforms: linux/amd64
+
+steps:
+  dryrun:
+    image: *buildx
+    settings:
+      <<: *buildx_settings
+      dry_run: true
+    when:
+      event: pull_request
+
+  generate_docker_tags:
+    image: bash
+    commands:
+      - grep 'TRANSMISSION_VERSION=' Dockerfile | sed s/.*=//g > .tags
+    when:
+      event: push
+
+  publish:
+    image: *buildx
+    settings:
+      <<: *buildx_settings
+      registry: gitea.aireone.xyz
+      repo: gitea.aireone.xyz/${CI_REPO,,}
+      auto_tag: true
+      username:
+        from_secret: publish_username
+      password:
+        from_secret: publish_token
+    when:
+      event: push