SomeJSONSchema does not accept correct JSONSchemaType object

**What version of Ajv are you using? Does the issue happen if you use the latest version?**

Latest: 8.11.0

**Ajv options object**

not applicable - errors with TS types

**Your code**

```ts
interface Body {
data: Record;
}

const bodySchema: JSONSchemaType = {
'$schema': 'https://json-schema.org/draft/2020-12/schema',
type: 'object',
properties: {
data: {
type: 'object',
},
},
required: ['data'],
};

export const eventSchema: SomeJSONSchema = {
'$schema': 'https://json-schema.org/draft/2020-12/schema',
type: 'object',
properties: {
body: bodySchema,
},
required: ['body'],
};
```

TS error:

```
TS2322: Type '{ $schema: string; type: "object"; properties: { body: { type: "object"; additionalProperties?: boolean | UncheckedJSONSchemaType | undefined; unevaluatedProperties?: boolean | ... 1 more ... | undefined; ... 7 more ...; maxProperties?: number | undefined; } & { ...; } & { ...; } & { ...; }; }; requi...' is not assignable to type 'SomeJSONSchema'.
  Types of property 'properties' are incompatible.
    Type '{ body: { type: "object"; additionalProperties?: boolean | UncheckedJSONSchemaType | undefined; unevaluatedProperties?: boolean | UncheckedJSONSchemaType | undefined; ... 7 more ...; maxProperties?: number | undefined; } & { ...; } & { ...; } & { ...; }; }' is not assignable to type 'Partial>'.
      Property 'body' is incompatible with index signature.
        Type '{ type: "object"; additionalProperties?: boolean | UncheckedJSONSchemaType | undefined; unevaluatedProperties?: boolean | UncheckedJSONSchemaType | undefined; ... 7 more ...; maxProperties?: number | undefined; } & { ...; } & { ...; } & { ...; }' is not assignable to type '{ $ref: string; } | (UncheckedJSONSchemaType & { const?: Known | undefined; enum?: readonly Known[] | undefined; default?: Known | undefined; }) | undefined'.
          Type '{ type: "object"; additionalProperties?: boolean | UncheckedJSONSchemaType | undefined; unevaluatedProperties?: boolean | UncheckedJSONSchemaType | undefined; ... 7 more ...; maxProperties?: number | undefined; } & { ...; } & { ...; } & { ...; }' is not assignable to type '{ $ref: string; }'.
            Types of property '$ref' are incompatible.
              Type 'string | undefined' is not assignable to type 'string'.
                Type 'undefined' is not assignable to type 'string'.
```

**What results did you expect?**

`SomeJSONSchema` should be possible to be composed of other valid schema objects.

**Are you going to resolve the issue?**

It can be over my possibilities.