build(woodpecker): run ci on next branch only and run full build

.woodpecker.yml

@@ -1,5 +1,8 @@
 steps:
   build:
+    when:
+      - event: push
+        branch: next
     image: rust:latest
     pull: true
     commands:
@@ -8,3 +11,4 @@ steps:
       - cargo fmt --check
       - cargo clippy --fix -- -Dwarnings -W clippy::nursery -W clippy::unwrap_used -W clippy::expect_used
       - cargo test
+      - cargo build