chore: update Kint to 4.2.0

[kenjis]

Description
Fixes #6429
See https://github.com/kint-php/kint/releases/tag/4.2.0

Checklist:

• Securely signed commits
• [] Component(s) with PHPDoc blocks, only if necessary or adds value
• [] Unit testing, with >80% coverage
• User guide updated
• [] Conforms to style guide

[paulbalandan]

Wait. Should we pin kint version to ^4.2?

[kenjis]

Should we pin kint version to ^4.2?

Done.

[MGatner]

I don't know why I haven't thought of this before but... shouldn't Kint be require-dev?

[kenjis]

shouldn't Kint be require-dev?

I don't know why but Kint is tightly coupled with CodeIgniter.
We can't disable it now.

[paulbalandan]

I don't know why I haven't thought of this before but... shouldn't Kint be require-dev?

If we are to agree that dd() is a testing-only function then we can move it to require-dev. But no, dd() is used by end users also, not just for the framework's testing use.