Flatbuffers: refer to Constants file to get current version.

Author: greenrobot-team

objectbox-java/src/main/java/io/objectbox/flatbuffers/README.md

@@ -3,8 +3,7 @@
 This is a copy of the [FlatBuffers](https://github.com/google/flatbuffers) for Java source code in a custom package
 to avoid conflicts with FlatBuffers generated Java code from users of this library.
 
-Current version: `1.12.0`
-(see also `Constants.java`).
+Current version: see `Constants.java`.
 
 Copy a different version using the script in `scripts\update-flatbuffers.sh`.