tests: Use Unicode literals in the Unicode decoding tests.

This is needed because the function returns Unicode strings and the
comparison will fail under python2 unless Unicode literals are used.

python/tests/group_session_test.py

@@ -125,7 +125,7 @@ class TestClass(object):
         plaintext, _ = inbound.decrypt(text)
 
         print(plaintext)
-        assert plaintext == "�"
+        assert plaintext == u"�"
 
         plaintext, _ = inbound.decrypt(text, "ignore")
         assert plaintext == ""

python/tests/pk_test.py

@@ -64,4 +64,4 @@ class TestClass(object):
         encryption = PkEncryption(decryption.public_key)
         message = encryption.encrypt(bytes([0xed]))
         plaintext = decryption.decrypt(message)
-        assert plaintext == "�"
+        assert plaintext == u"�"

python/tests/session_test.py

@@ -151,4 +151,4 @@ class TestClass(object):
 
         bob_session = InboundSession(bob, message)
         plaintext = bob_session.decrypt(message)
-        assert plaintext == "�"
+        assert plaintext == u"�"