Auth UserRecord class missing passwordUpdatedAt property

* Operating System version: MacOS 3.2
* Firebase SDK version: 11.4.1
* Firebase Product: auth
* Node.js version: 18.13.0
* NPM version: 8.19.3

### [REQUIRED] Step 3: Describe the problem

#### Steps to reproduce:

The `getUser` function wraps a call to the REST API method getAccountInfo:
https://developers.google.com/resources/api-libraries/documentation/identitytoolkit/v3/python/latest/identitytoolkit_v3.relyingparty.html#getAccountInfo

That API method exposes a `passwordUpdatedAt` property. However, the Admin SDK is instantiating a UserRecord class from the response which is missing that property. This property is useful in order to track password changes (e.g., send alert email to user that password was changed).

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