fix: joi transform

[alexanderniebuhr]

actually, the issue was with the used transformation lib
changed to one which is updated more recently
closes #373

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

[mcollina]

Can you please add a test with this new lib as well?

fastify-swagger/package.json

Line 43 in 9ec48ec

"joi-to-json-schema": "^5.1.0",

[climba03003]

I think a documentation is needed for joi
joi-to-json-schema can be use before this commit and it suppose to be < 16.0.0
joi-to-json only support what it state.

[alexanderniebuhr]

@climba03003 feel free to add on this PR. However I think it is better to have a lib which supports latest joi..

[coveralls]

Pull Request Test Coverage Report for Build 617305534

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 617156967:	0.0%
Covered Lines:	457
Relevant Lines:	457

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 617461435

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

---

Totals
Change from base Build 617156967:	0.0%
Covered Lines:	457
Relevant Lines:	457

---

💛 - Coveralls

[mcollina]

lgtm

[climba03003]

Would you mind to add a full example for joi in examples folder?

[alexanderniebuhr]

@climba03003 example in #377

[climba03003]

@climba03003 example in #377

Thanks for your works.