Fix pyarmnn Unittest failure in Master

* Update more-itertools to 8.12

Signed-off-by: Nikhil Raj <nikhil.raj@arm.com>
Change-Id: I572340793db0e7da993679466d723c61d6d2bab2
diff --git a/python/pyarmnn/tox.ini b/python/pyarmnn/tox.ini
index be3118b..3ba47c1 100644
--- a/python/pyarmnn/tox.ini
+++ b/python/pyarmnn/tox.ini
@@ -13,7 +13,7 @@
        numpy==1.17.2
        pillow==6.1.0
        requests==2.23.0
-       more-itertools==8.10.0
+       more-itertools==8.12.0
 
 recreate = True
 allowlist_externals = /bin/sh