Update utility.ts

Make Little Endian serialiser exportable.

Pls correct me if this is not needed

packages/core/src/utility.ts

@@ -53,7 +53,7 @@ export const serialiseUint32 = (n: number): Buffer => {
     return buf;
 };
 
-const serialiseUint32LE = (n: number): Buffer => {
+export const serialiseUint32LE = (n: number): Buffer => {
     const buf = Buffer.alloc(4);
     buf.writeUInt32LE(n);
     return buf;