feat!: drop node@14 support for mongodb@6 driver

[climba03003]

Refs https://github.com/mongodb/node-mongodb-native/releases/tag/v6.0.0
Refs fastify/fastify-mongodb#219

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[Eomm]

mmm we have only one release line:

• I would drop node.js 14 from every workflow and bump a major that we will use only on fastify-mongo
• OR: we add a new parameter to skip some nodejs version.. I needed it the past week 😄

[Uzlopak]

I had somewhere the script for specifying the node version

[climba03003]

I use the hash version inside fastify-mongodb, so it is not a problem for now.

[Fdawgs]

@climba03003 @gurgunday This may have just been superceded by #124 ?