package:collection v1.19.0

• Adds shuffled to IterableExtension.
• Shuffle IterableExtension.sample results.
• Fix mergeSort when the runtime iterable generic is a subtype of the static
  generic.
• CanonicalizedMap: added constructor fromEntries.
• Mark "mixin" classes as mixin.
• extension IterableIterableExtension<T> on Iterable<Iterable<T>>
  • Add flattenedToList as a performance improvement over flattened.
  • Add flattenedToSet as new behavior for flattening to unique elements.
• Deprecate transitiveClosure. Consider using package:graphs.
• Deprecate whereNotNull() from IterableNullableExtension. Use nonNulls
  instead - this is an equivalent extension available in Dart core since
  version 3.0.
• Require Dart ^3.4.0