Bump ffigen from 17.0.0 to 18.0.0 in /packages/dartcv

Bumps [ffigen](https://github.com/dart-lang/native/tree/main/pkgs) from 17.0.0 to 18.0.0.
- [Release notes](https://github.com/dart-lang/native/releases)
- [Commits](https://github.com/dart-lang/native/commits/ffigen-v18.0.0/pkgs)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Diff for: packages/dartcv/pubspec.yaml

@@ -13,7 +13,7 @@ dependencies:
   ffi: ^2.1.3
 
 dev_dependencies:
-  ffigen: ">=13.0.0 <18.0.0"
+  ffigen: ">=13.0.0 <19.0.0"
   test: ^1.25.2
 
 topics: