Fix:Puppeteer reports a weird warning (#247)

[thunderhunt]

Fixed the weird warning, and bumped up the puppeteer version.

[simonhaenisch]

The dependency has such a wide range on purpose for deduplication reasons when using md-to-pdf in projects that already use puppeteer.

[simonhaenisch]

I don't think this needs to be fixed... it's just a deprecation warning, the change in Puppeteer will have no actual impact on the output of md-to-pdf afaik.

[thunderhunt]

I don't think this needs to be fixed... it's just a deprecation warning, the change in Puppeteer will have no actual impact on the output of md-to-pdf afaik.

Agreed, but it give a big yellow warning , which may not be very comfortable for the users to see when they try out the tool. So thought to handle.

[thunderhunt]

@simonhaenisch Can we merge this PR? As It panics new users with that weird msg.

[simonhaenisch]

The headless: 'new' config change yeah we can merge but can you please verify that the --devtools flag still works (i.e. when you run md-to-pdf --devtools, it opens the browser, i.e. headful mode, with the rendered page, and opens dev tools).

The package.json and package-lock.json changes I don't want, please revert them.