chore(wbn-sign): fix ESLint errors

Remove the unused `crypto` import from integrity-block-signer.ts and unused
destructured variables from utils_test.js, so that `npx eslint .` passes.

Author: zgroza

js/sign/src/signers/integrity-block-signer.ts

@@ -1,5 +1,5 @@
 import assert from 'assert';
-import crypto, { KeyObject } from 'crypto';
+import { KeyObject } from 'crypto';
 
 import { encode } from 'cborg';
 

js/sign/tests/utils_test.js

@@ -6,7 +6,7 @@ import * as utils from '../lib/utils/utils.js';
 describe('Utils', () => {
   describe('parseRawPublicKey', () => {
     it('correctly parses an Ed25519 raw public key', () => {
-      const { publicKey, privateKey } = crypto.generateKeyPairSync('ed25519');
+      const { publicKey } = crypto.generateKeyPairSync('ed25519');
       // Export to raw bytes
       const spki = publicKey.export({ type: 'spki', format: 'der' });
       const rawPublicKey = new Uint8Array(spki.subarray(-32));
@@ -23,7 +23,7 @@ describe('Utils', () => {
     });
 
     it('correctly parses an ECDSA P-256 raw public key (compressed)', () => {
-      const { publicKey, privateKey } = crypto.generateKeyPairSync('ec', {
+      const { publicKey } = crypto.generateKeyPairSync('ec', {
         namedCurve: 'prime256v1',
       });
       const spki = publicKey.export({ type: 'spki', format: 'der' });