[zod-openapi] generateSchema always returns 3.1 SchemaObject even when 3.0 is requested

[naighes]

The function generateSchema accepts an openApiVersion parameter with values '3.0' | '3.1'.
However, even when '3.0' is passed, the returned type is always the 3.1 SchemaObject:

const schema = generateSchema(some_schema, true, '3.0')
// typescript infers schema as SchemaObject (3.1)

This causes type errors when using openapi3-ts/oas30.
I think it's going to be quite tricky, but I guess you should do something like this:

export function generateSchema<
  V extends '3.0' | '3.1' = '3.1'
>(
  zodRef: OpenApiZodAny,
  useOutput = false,
  openApiVersion?: V,
): V extends '3.0' ? SchemaObject30 : SchemaObject31 {
  // ...snip...
}