Passcode entry backspace not working

### ⚠️ Before posting ⚠️

- [X] This is a **bug**, not a question or an enhancement.
- [X] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [X] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [X] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

1. Set up Nextcloud app
2. Open *Settings* tab
3. Tap *App passcode* and select the *Passcode* option
4. Enter three digits
5. Press ⌫ on the on-screen keyboard

### Expected behaviour

The digit last entered should be deleted from the input.

### Actual behaviour

Nothing happens.

### Android version

11 (API level 30; AOSP image)

### Device brand and model

Google Pixel 2 Emulator (Android Studio)

### Stock or custom OS?

Stock

### Nextcloud android app version

2d02398391c398f4758f8d7b526beeaab5de892d

### Nextcloud server version

27.0.1

### Using a reverse proxy?

No

### Android logs

_No response_

### Server error logs

_No response_

### Additional information

https://github.com/nextcloud/android/pull/12068#pullrequestreview-1714789828

When using an external keyboard, a single press leads to multiple characters being input or deleted at once.