Incorrectly loose types for strict object schema for non-string values

#### Support plan

* *is this issue currently blocking your project?* (yes/no): no
* *is this issue affecting a production system?* (yes/no): no

#### Context

* *node version*: 20.0.5
* *module version with issue*: 17.11.0, master branch
* *last module version without issue*:
* *environment* (e.g. node, browser, native): node
* *used with* (e.g. hapi application, another framework, standalone, ...): standalone
* *any other relevant information*:

#### What are you trying to achieve or the steps to reproduce?

```ts
interface User2 {
id?: number
}

Joi.object({
id: Joi.string().optional()
});
```

#### What was the result you got?

No warning despite id being string

#### What result did you expect?

Typescript warning that string schema is not assignable to number schema

This seems to work as a fix, I would create a PR but I couldn't get the test to work correctly, it still said `Expected an error` even though after the change TypeScript warned about it