chore(deps): Bump the xml group in /packages/smithy/smithy with 1 update

Bumps the xml group in /packages/smithy/smithy with 1 update: [xml](https://github.com/renggli/dart-xml).

- [Changelog](https://github.com/renggli/dart-xml/blob/main/CHANGELOG.md)
- [Commits](renggli/dart-xml@6.3.0...6.4.2)

---
updated-dependencies:
- dependency-name: xml
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: xml
...

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

packages/smithy/smithy/pubspec.yaml

@@ -25,7 +25,7 @@ dependencies:
   retry: ^3.1.0
   shelf: ^1.1.0
   typed_data: ^1.3.0
-  xml: 6.3.0
+  xml: 6.4.2
 
 dev_dependencies:
   amplify_lints: ">=3.0.0 <3.1.0"