introspectAccessToken does not return response data

[ZLeventer]

Description

The introspectAccessToken method makes the API call correctly but does not return response.data to the caller. The return value is undefined instead of the token introspection payload.

Steps to reproduce

const result = await client.introspectAccessToken(token);
console.log(result); // undefined — expected the introspection response

Expected behavior

The method should return the introspection response object containing active, client_id, scope, etc.

Suggested fix

Add return response.data to the method. See PR #40.