[BUG] Demo crash when take a photo in IOS

[JasonHezz]

Describe the bug (描述)
After click pick from camera, app will crash in IOS.

How to reproduce (如何复现)
Please provide a minimum demo rather than a full project or a incomplete pages. Otherwise we have rights to reject your request.
Project example

Steps to reproduce the behavior (描述复现步骤):

1. Go to homepage
2. Click on 'Pick from camera'
3. See error

Expected behavior (期望行为)
No crash and take a photo

Screenshots (If contains) (是否有截图可以提供)
If applicable, add screenshots to help explain your problem.

Device information (设备信息)

• Device: iPhone X
• OS: IOS 13.5.1
• Package Version: 4.1.0+2
• Flutter Version: 1.20.0-7.2.pre

Additional context (附加信息)
stacktrace
[access] This app has crashed because it attempted to access privacy-sensitive data without a usage description. The app's Info.plist must contain an NSCameraUsageDescription key with a string value explaining to the user how the app uses this data.

Workaround:
Add following content to info.plist.

<key>NSCameraUsageDescription</key>
<string>Take a photo for display</string>