secure_pubspec_urls  
            
            Use secure urls in pubspec.yaml.
This rule is available as of Dart 2.16.0.
Details
DO Use secure urls in pubspec.yaml.
Use https instead of http or git:.
BAD:
repository: http://github.com/dart-lang/example
git:
  url: git://github.com/dart-lang/example/example.git
GOOD:
repository: https://github.com/dart-lang/example
Usage
To enable the secure_pubspec_urls rule,
add secure_pubspec_urls under linter > rules in your
analysis_options.yaml
file:
linter:
  rules:
    - secure_pubspec_urls