Update ffi package version (#3376)

Author: sgrekhov

LibTest/ffi/pubspec.yaml

@@ -1,11 +1,11 @@
 name: co19_ffi
 description: co19 tests for Dart FFI library
 
-# This tests isn't intended for publishing on pub.dev.
+# These tests aren't intended for publishing on pub.dev.
 publish_to: none
 
 environment:
   sdk: '>=3.3.0-279.1.beta <4.0.0'
 
 dependencies:
-  ffi: ^2.1.0
+  ffi: ^2.1.4