remove lint (broken in prepare-worker)

This lint doesn't work with multiple targets (in the case of prepare-worker, the
bench-only dependencies were messing it up). See:

- rust-lang/rust#95513
- rust-lang/rust#57274 (comment)

polkadot/node/core/pvf/prepare-worker/src/lib.rs

@@ -16,7 +16,6 @@
 
 //! Contains the logic for preparing PVFs. Used by the polkadot-prepare-worker binary.
 
-#![deny(unused_crate_dependencies)]
 #![warn(missing_docs)]
 
 mod memory_stats;