FFI: declare compatible with version 2.x.x.

Author: greenrobot-team

objectbox/pubspec.yaml

@@ -13,7 +13,7 @@ dependencies:
   collection: ^1.15.0
   # take care updating flatbuffers - keep aligned with other bindings
   flat_buffers: 2.0.5
-  ffi: ^1.0.0
+  ffi: '>=1.0.0 <3.0.0'
   meta: ^1.3.0
   path: ^1.8.0