chore(deps): update sealed_countries dependency to v3.1.0

This updates the sealed_countries dependency version from 3.0.1 to 3.1.0 in world_flags.

docs: simplify language flag leading logic in example app

Updated the leading property in LanguageTileThemeData to remove
the alternativeMap parameter, streamlining the flag retrieval
for languages with multiple countries.

chore(docs): add fossa license status badge

This adds a badge to indicate the license compliance status of the project in the README.

refactor: implement conditional imports for platform environment (#483)

* refactor: implement conditional imports for platform environment

- Added platform-specific implementations for environment handling.
- Introduced conditional imports in platform_environment.dart to support
  different platforms (IO, web).

* refactor: update changelog and pubspec.yaml for platform support

- Added `platforms` section to `pubspec.yaml` to declare support for all official Flutter platforms.
- Updated version in example `pubspec.yaml` to 3.0.1.
- Improved clarity in CHANGELOG.

* refactor: enhance benchmark runner with command logging and dependency upgrade

- Added logging for command execution in _runCommand.
- Included a step to upgrade dependencies in _buildApk.
- Improved argument formatting for command execution.

world_flags-v3.0.0

chore: `world_flags` v3.0.0

chore: `world_countries` v4.0.0 (#471)

* feat: add iso maps builder to locale delegate for map customization

- Introduced isoMapsBuilder parameter to allow mutation of IsoMaps
- Updated tests to verify behavior of isoMapsBuilder in TypedLocaleDelegate

* chore: update version to 4.0.0 and adjust changelog for new features

- Updated application version in about dialog and pubspec files.
- Added new features to changelog including animated shader delegates.

chore(ci): update ubuntu version in backup workflow

Changed the runner from ubuntu-slim to ubuntu-latest for better support.