Error: Unable to 'pub upgrade' flutter tool

Question

I'm a newbie in flutter, what should I do in this case? Thank you all.

This is the Error message

Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds... (9 tries left) Error on line 14, column 6 of pubspec.yaml: Expected ':'.

dds: 2.0.4 ^

and in the line 14, it's a comment out like this

# Read more about Android versioning at https://developer.android.com/studio/publish/versioning

I can't figure it out what cause this error

This is my pubspec.yaml file

version: 1.0.0+1

environment:
  sdk: ">=2.12.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  firebase_auth: ^3.1.4
  cloud_firestore: ^2.5.3
  firebase_core: ^1.8.0
  firebase_storage: ^10.0.6
  provider: ^6.0.1
  image_picker: ^0.8.4+3
  file_picker: ^4.1.6
  transparent_image: ^2.0.0
  shared_preferences: ^2.0.8
  qr_code_scanner: ^0.5.2
  cupertino_listview: ^2.0.0
  zefyr: ^0.12.0

  cupertino_icons: ^1.0.2
  image_picker_for_web: ^2.1.4
  firebase_storage_web: ^3.0.4
  shared_preferences_web: ^2.0.2
  url_launcher_web: ^2.0.4


dev_dependencies:
  flutter_test:
    sdk: flutter

  flutter_lints: ^1.0.0

flutter:
  uses-material-design: true
  assets:
    - assets/images/

When I use flutter command, it always jump out This is the Error message

Error: Unable to 'pub upgrade' flutter tool. Retrying in five seconds... (9 tries left) Error on line 14, column 6 of pubspec.yaml: Expected ':'.

dds: 2.0.4 ^