equatable 2.1.0: Verify that Equatable does not automatically stringify properties in toString() unless explicitly enabled

When overriding `props` in a class extending `Equatable`, it is common to assume that `toString()` will automatically return a formatted string of the object's properties (e.g. `User(alice)`). 

However, by default, `toString()` only returns the class name. To include the properties, one must explicitly override `bool get stringify => true;` or configure `EquatableConfig.stringify = true;` globally.

The `search_known_solution` lookup yielded two different samples for this library: one covering `runtimeType` checks preventing equality for generics, and another covering basic value equality. This sample demonstrates the default `stringify` behavior instead.

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# Generated by pub
# See https://dart.dev/tools/pub/glossary#lockfile
packages:
  collection:
    dependency: transitive
    description:
      name: collection
      sha256: "2f5709ae4d3d59dd8f7cd309b4e023046b57d8a6c82130785d2b0e5868084e76"
      url: "https://pub.dev"
    source: hosted
    version: "1.19.1"
  equatable:
    dependency: "direct main"
    description:
      name: equatable
      sha256: "3bce007a596ff8b3119c45d68aaef631272537c03d30e5d4534dd24bf4c5eaa2"
      url: "https://pub.dev"
    source: hosted
    version: "2.1.0"
  meta:
    dependency: transitive
    description:
      name: meta
      sha256: "307249ce4ff29d58a18e97f6345f539382eb9c9c29ecda628900f31de0443dd9"
      url: "https://pub.dev"
    source: hosted
    version: "1.19.0"
sdks:
  dart: ">=3.5.0 <4.0.0"

name: sample
environment:
  sdk: '>=3.0.0 <4.0.0'
dependencies:
  equatable: ^2.1.0

import 'package:equatable/equatable.dart';

class User extends Equatable {
  final String name;
  const User(this.name);
  
  @override
  List<Object?> get props => [name];
}

void main() {
  if (User('alice').toString() != 'User') throw 'toString defaults to just the class name, not the formatted props';
}

import 'package:equatable/equatable.dart';

class MyClass extends Equatable {
  final String id;
  const MyClass(this.id);
  
  @override
  List<Object?> get props => [id];
}

void main() {
  final obj = MyClass('abc');
  print('stringify is: ${obj.stringify}');
  print('toString returns: ${obj.toString()}');
}