Node.js v19 Breaking Change

[RafaelGSS]

Hello!

I'm opening this PR just to inform the new Node.js release v19 might break a few users that expect the connection will be closed after the first request.

Example:

sget({
        method: 'POST',
        url: 'localhost:3000',
      }, (err, res, body) => {
        ...
      })

sget({
        method: 'POST',
        url: 'localhost:3000',
        agent: false, // this will obligate creating an agent for every request, so the connection won't be reutilized by default
      }, (err, res, body) => {
        ...
      })

[JulienBrgs]

I confirm this cause problem with node 20.x in my case