Update the tools setup.cfg for flatbuffers 2.0

Aligns with the changes to the serialization library

Signed-off-by: Eric Kunze <eric.kunze@arm.com>
Change-Id: I3e262590e62e941c5385ad55408688dd1c20d158
diff --git a/setup.cfg b/setup.cfg
index 1140c9c..1e4c55d 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -20,7 +20,7 @@
 [options]
 install_requires =
     numpy
-    flatbuffers == 1.12
+    flatbuffers == 2.0
 python_requires = >=3.6
 include_package_data = True
 packages =