fix: watcher ignores ts files in typescript projects

[alemagio]

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

This patch was included as a comment here, it should be included in the template and be like that out of the box.

Without this change we have a weird behavior between the typescript watcher and the CLI watcher.
CLI watcher basically restart before the TS compiler finishes its job so the changes are not visible immediately.

[mcollina]

lgtm

[climba03003]

LGTM. it can ensure fastify-cli only restart when the compiled code change.

[alemagio]

LGTM. it can ensure fastify-cli only restart when the compiled code change.

Exactly

[RafaelGSS]

LGTM. Good catch!