Password changes don't work on Conduit

### Steps to reproduce

Password change flow does not work on Conduit, server is returning `Malformed JSON`
This might be the same issue as vector-im/element-android#8043

## What was expected
After inserting the new password and clicking the change password button the password is effectively changed

## What happens instead
Password is not changed and `Malformed JSON` is returned by the app

### Your phone model

iPhone 11 Pro

### Operating system version

iOS 16.3.1

### Application version

1.10.2

### Homeserver

_No response_

### Will you send logs?

Yes