Update dependency collection to v1.19.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
collection	dependencies	minor	1.18.0 -> 1.19.0

---

Release Notes

dart-lang/collection (collection)

### [`v1.19.0`](https://togithub.com/dart-lang/collection/blob/HEAD/CHANGELOG.md#1190) [Compare Source](https://togithub.com/dart-lang/collection/compare/v1.18.0...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 on Iterable>` - 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`

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.

[renovate[bot]]

Renovate Ignore Notification

Because you closed this PR without merging, Renovate will ignore this update (1.19.0). You will get a PR once a newer version is released. To ignore this dependency forever, add it to the ignoreDeps array of your Renovate config.

If you accidentally closed this PR, or if you changed your mind: rename this PR to get a fresh replacement PR.