Remove upstream GCM issue that was resolved

diff --git a/deltatar/crypto.py b/deltatar/crypto.py
index b0c863c..80850b3 100755 (executable)
--- a/deltatar/crypto.py
+++ b/deltatar/crypto.py
@@ -24,9 +24,6 @@ References:
     - Authentication weaknesses in GCM
       http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/comments/CWC-GCM/Ferguson2.pdf
 
-Trouble with python-cryptography packages: authentication tags can only be
-passed in advance: https://github.com/pyca/cryptography/pull/3421
-
 Errors
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