Fix mistake (missing type hint)

Author: jtraglia

pysetup/spec_builders/electra.py

@@ -47,7 +47,7 @@ def get_payload(self: ExecutionEngine, payload_id: PayloadId) -> GetPayloadRespo
 
     def is_valid_block_hash(self: ExecutionEngine,
                             execution_payload: ExecutionPayload,
-                            parent_beacon_block_root,
+                            parent_beacon_block_root: Root,
                             execution_requests_list: Sequence[bytes],
                             target_blobs_per_block: uint64) -> bool:
         return True