beacon/types: update for fulu (#33349)

Should fix decoding JSON blocks in the Fulu fork. This diff was missing
from #33349.

Author: fjl

beacon/types/beacon_block.go

@@ -52,7 +52,7 @@ func BlockFromJSON(forkName string, data []byte) (*BeaconBlock, error) {
 		obj = new(capella.BeaconBlock)
 	case "deneb":
 		obj = new(deneb.BeaconBlock)
-	case "electra":
+	case "electra", "fulu":
 		obj = new(electra.BeaconBlock)
 	default:
 		return nil, fmt.Errorf("unsupported fork: %s", forkName)

beacon/types/exec_header.go

@@ -45,7 +45,7 @@ func ExecutionHeaderFromJSON(forkName string, data []byte) (*ExecutionHeader, er
 	switch forkName {
 	case "capella":
 		obj = new(capella.ExecutionPayloadHeader)
-	case "deneb", "electra": // note: the payload type was not changed in electra
+	case "deneb", "electra", "fulu": // note: the payload type was not changed in electra/fulu
 		obj = new(deneb.ExecutionPayloadHeader)
 	default:
 		return nil, fmt.Errorf("unsupported fork: %s", forkName)