Chores: Update example, widen flutter_lints constraints, update version and changelog

[nohli]

flutter create . and update Android dependencies

When running the example from main on Android, it fails due to several reasons:

Launching lib/main.dart on Pixel 3 in debug mode...
Running Gradle task 'assembleDebug'...
You are applying Flutter's main Gradle plugin imperatively using the apply script method, which is deprecated and will be removed in a future release. Migrate to applying Gradle plugins with the declarative plugins block: https://flutter.dev/go/flutter-gradle-plugin-apply

Warning: unable to detect project KGP version. Skipping version checking. 
This may be because you have applied KGP after the Flutter Gradle Plugin.

FAILURE: Build failed with an exception.

* Where:
Build file '/Users/achim/code/packages/flutter_hsvcolor_picker/example/android/build.gradle' line: 24

* What went wrong:
A problem occurred evaluating root project 'android'.
> A problem occurred configuring project ':app'.
   > Could not create an instance of type com.android.build.api.variant.impl.ApplicationVariantImpl.
      > Namespace not specified. Specify a namespace in the module's build file. See https://d.android.com/r/tools/upgrade-assistant/set-namespace for information about setting the namespace.

        If you've specified the package attribute in the source AndroidManifest.xml, you can use the AGP Upgrade Assistant to migrate to the namespace value in the build file. Refer to https://d.android.com/r/tools/upgrade-assistant/agp-upgrade-assistant for general information about using the AGP Upgrade Assistant.

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 20s
Error: Gradle task assembleDebug failed with exit code 1

Therefore, I recreated the Android folder, and updated the dependencies.

This PR also adds the folders for starting the example app on all other Flutter-supported platforms.

Doing maintenance, I also widened the constraints for flutter_lints to support 4.0.0 without introducing a breaking change.

[nohli]

@AlexV525 the pub publish action is stuck on authentication - can you please update the secret CREDENTIAL_JSON for this repo?

To make it easier:

1. flutter pub logout
2. flutter pub login
3. cat ~/Library/"Application Support"/dart/pub-credentials.json