chore: fix clippy lints to green the lint CI

- import.rs / promotion.rs: sort_by(|a,b| b.k.cmp(&a.k)) -> sort_by_key(Reverse(k))
- pipeline.rs: skip_while(!p).next() -> find(p)
Behaviour-preserving; completes the CI fix started by the cargo fmt commit.

src/promotion.rs

@@ -272,7 +272,7 @@ impl Promotion {
                 )
             })
             .collect();
-        out.sort_by(|a, b| b.2.cmp(&a.2));
+        out.sort_by_key(|x| std::cmp::Reverse(x.2));
         out
     }