Discussion: Proposed Changes for expressjs/response-time Next Major Version

This issue aims to discuss potential changes for the next major version of `expressjs/response-time`.

### Key Areas to Consider:

1. API Simplification - BREAKING CHANGE

- **Standardized Options Object**: Remove the deprecated approach of passing a single number to the middleware. Going forward, users should provide options as an object:
```javascript
app.use(responseTime({ digits: 3 })); // Set digits to 3
```
2. Node.js Version Support - BREAKING CHANGE
Drop support for Node.js < 18: We propose discontinuing support for Node.js versions below 18 (LTS). This ensures alignment with the latest security patches and modern features of Node.js.

3. Dependency Management
Upgrade dependencies: Update all project dependencies to their latest compatible versions, ensuring access to bug fixes, security updates, and compatibility with Node.js 18+.

4. Code Modernization - BREAKING CHANGE
Migrate to new ES syntax: Consider refactoring the codebase to leverage modern ES syntax, improving maintainability and alignment with contemporary Node.js practices.