Update CHANGELOG reference for Cardinal security fix.
Update CHANGELOG reference for Cardinal security fix.

Signed-off-by: Steven Shropshire <e0eaefab33cb0c3d300c8879d154a2846a56c9dd@getbraintree.com>

braintree/braintree_android,braintree/braintree_android,braintree/braintree_android,braintree/braintree_android