🐛 Bug Report: Encryption property is null

### 👟 Reproduction steps

When I use library version > 20.3.3 and trying to upload a file to storage I got an error:

```
type 'Null' is not a subtype of type 'bool'
file.dart:73
storage.dart:81
```

It seems the "encryption" property do not exist on self hosted server 1.8.x.
So is all version > 20.3.3 are only compatible with 1.9.x? (because there is no indication on the compatible version in the Readme)

### 👍 Expected behavior

It should works OR need to be explicit in the README when not compatible (it's the case for the last one version but not for all other > 20.3.3)

### 👎 Actual Behavior

It crash when trying to upload a file

### 🎲 Appwrite version

Different version (specify in environment)

### 💻 Operating system

Linux

### 🧱 Your Environment

Appwrite latest 1.8.1 self hosted

### 👀 Have you spent some time to check if this issue has been raised before?

- [x] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [x] I have read the [Code of Conduct](https://github.com/appwrite/appwrite/blob/HEAD/CODE_OF_CONDUCT.md)