Updating the barracuda 1.4.0 (#5291)

com.unity.ml-agents/CHANGELOG.md

 sizes and will need to be retrained. (#5181)
 - The `AbstractBoard` class for integration with Match-3 games was changed to make it easier to support boards with
 different sizes using the same model. For a summary of the interface changes, please see the Migration Guide. (##5189)
-- Updated the Barracuda package to version `1.3.3-preview`(#5236)
+- Updated the Barracuda package to version `1.4.0-preview`(#5236)
 - `GridSensor` has been refactored and moved to main package, with changes to both sensor interfaces and behaviors.
 Exsisting GridSensor created by extension package will not work in newer version. Previously trained models will
 need to be retrained. Please see the Migration Guide for more details. (#5256)

com.unity.ml-agents/package.json

   "unity": "2019.4",
   "description": "Use state-of-the-art machine learning to create intelligent character behaviors in any Unity environment (games, robotics, film, etc.).",
   "dependencies": {
-    "com.unity.barracuda": "1.3.3-preview",
+    "com.unity.barracuda": "1.4.0-preview",
     "com.unity.modules.imageconversion": "1.0.0",
     "com.unity.modules.jsonserialize": "1.0.0"
   }