Replace any with unknown

[Leo5878]

This is one of the changes for my issue about generating types using unknown instead of any.
I tried to fix the tests, but I didn’t really manage to.

[JasonShin]

Thanks for this, it's a great improvement to enforce stricter typing where sqlx-ts cannot infer proper types "yet" and encourages consumers to properly acknowledge and handle the unknown type (aka alias it or type-guard it)

[JasonShin]

I don't have a permission to push to this branch, so I created a new one here #264 🙏

Thanks for your contributions!