Update fastify to v3

[frikille]

• Updated fastify to v3
• Added dependabot config

This PR unblocks fastify/fastify#2217

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 Code of conduct

[Fdawgs]

Superceded by #18