ci: use variables

.woodpecker.yml

@@ -2,11 +2,12 @@ pipeline:
   docker:
     image: woodpeckerci/plugin-docker-buildx
     settings:
-      username: bot
+      username:
+        from_secret: registry_username
       password:
-        from_secret: nexus_password
+        from_secret: registry_password
-      repo: docker.nyyu.dev/nyyu/pyload-ng
+      repo: ${DOCKER_REGISTRY}/${CI_REPO_OWNER}/pyload-ng
-      registry: docker.nyyu.dev
+      registry: ${DOCKER_REGISTRY}
       tags: latest
     when:
       branch: main