add miss retrun type

test/utils.test.ts

 import { Utils } from '../src/utils';
 
-test('utils crc32', () => {
+test('utils crc32', (): void => {
   const v = Utils.crc32('/v1/session/init');
   expect(v).toBe(1897767088);
 });
 
-test('utils str2ab and ab2str', () => {
+test('utils str2ab and ab2str', (): void => {
   expect(Utils.ab2str(Utils.str2ab('test'))).toBe('test');
 });
 
-test('utils encrypt and decrypt', () => {
+test('utils encrypt and decrypt', (): void => {
   const key = 'b8ca9aa66def05ff3f24919274bb4a66';
   const iv = key;
   expect(Utils.decrypt(Utils.encrypt('test', key, iv), key, iv)).toBe('test');
 });
 
-test('utils binToBase64 and base64ToBin', () => {
+test('utils binToBase64 and base64ToBin', (): void => {
   expect(Utils.binToBase64(Utils.base64ToBin('test'))).toBe('test');
 });
 
-test('utils stringToBin and binToString', () => {
+test('utils stringToBin and binToString', (): void => {
   expect(Utils.binToString(Utils.stringToBin('test'))).toBe('test');
 });