build: (deps): bump matrix from 4.1.0 to 5.0.0

Bumps [matrix](https://github.com/famedly/matrix-dart-sdk) from 4.1.0 to 5.0.0.
- [Release notes](https://github.com/famedly/matrix-dart-sdk/releases)
- [Changelog](https://github.com/famedly/matrix-dart-sdk/blob/main/CHANGELOG.md)
- [Commits](https://github.com/famedly/matrix-dart-sdk/compare/v4.1.0...v5.0.0)

---
updated-dependencies:
- dependency-name: matrix
  dependency-version: 5.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

lib/utils/matrix_sdk_extensions/event_extension.dart

@@ -41,11 +41,11 @@ extension LocalizedBody on Event {
 
   bool get isAttachmentSmallEnough =>
       infoMap['size'] is int &&
-      infoMap['size'] < room.client.database.maxFileSize;
+      (infoMap['size'] as int) < room.client.database.maxFileSize;
 
   bool get isThumbnailSmallEnough =>
       thumbnailInfoMap['size'] is int &&
-      thumbnailInfoMap['size'] < room.client.database.maxFileSize;
+      (thumbnailInfoMap['size'] as int) < room.client.database.maxFileSize;
 
   bool get showThumbnail =>
       [