fix: update jws to 4.0.0 to resolve SlowBuffer deprecation

[l7aromeo]

Description

This PR updates the jws dependency from 3.2.2 to 4.0.0 to resolve compatibility issues with Node.js 25+, where the SlowBuffer constructor has been removed.

Problem:
The current dependency chain includes an outdated version of jwa (1.4.1) that depends on buffer-equal-constant-time, which uses the deprecated SlowBuffer API. This causes the library to crash on Node.js 25 with the error:

TypeError: Cannot read properties of undefined (reading 'prototype')

Solution:
Updating jws to 4.0.0 brings in jwa 2.0.0, which replaced buffer-equal-constant-time with Node.js's native crypto.timingSafeEqual() method (introduced in jwa 1.4.2).

Dependency chain:

• Before: jsonwebtoken → jws 3.2.2 → jwa 1.4.1 → buffer-equal-constant-time (uses SlowBuffer ❌)
• After: jsonwebtoken → jws 4.0.0 → jwa 2.0.0 → crypto.timingSafeEqual (native, no SlowBuffer ✅)

Compatibility:

• ✅ Node.js 25+ (SlowBuffer removed)
• ✅ Node.js 22 LTS
• ✅ Node.js 20 LTS
• ✅ Node.js 18 LTS

This is a non-breaking change as jws 4.0.0 maintains API compatibility with 3.x.

References

• Node.js 25 Release Notes: https://nodejs.org/en/blog/release/v25.0.0 (SlowBuffer removal)
• jwa v1.4.2 changelog: Replaced buffer-equal-constant-time with crypto.timingSafeEqual

Testing

Manual Testing:

• Tested on Node.js 25.0.0 - library loads and functions correctly ✅
• Tested on Node.js 22.12.0 (LTS) - backward compatibility confirmed ✅
• Tested on Node.js 20.18.1 (LTS) - backward compatibility confirmed ✅

Test Commands:

# Install and verify
npm install
npm test

# Verify JWT operations work
node -e "const jwt = require('./'); const token = jwt.sign({foo: 'bar'}, 'secret'); console.log(jwt.verify(token, 'secret'));"

Environment:

• Node.js: 25.0.0, 22.12.0, 20.18.1
• npm: 10.x/11.x
• OS: macOS 26.1

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
  • No documentation changes needed - this is an internal dependency update with no API changes
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not the default branch