tests: Simplify the input parameter for the Unicode decoding tests.

python/tests/group_session_test.py

 # -*- coding: utf-8 -*-
-
-from builtins import bytes
-
 import pytest
 
 from olm import InboundGroupSession, OlmGroupSessionError, OutboundGroupSession
@@ -121,7 +118,7 @@ class TestClass(object):
         outbound = OutboundGroupSession()
         inbound = InboundGroupSession(outbound.session_key)
 
-        text = outbound.encrypt(bytes([0xed]))
+        text = outbound.encrypt(b"\xed")
         plaintext, _ = inbound.decrypt(text)
 
         print(plaintext)

python/tests/pk_test.py

 # -*- coding: utf-8 -*-
-from builtins import bytes
-
 import pytest
 
 from olm import (PkDecryption, PkDecryptionError, PkEncryption, PkSigning,
@@ -62,6 +60,6 @@ class TestClass(object):
     def test_invalid_unicode_decrypt(self):
         decryption = PkDecryption()
         encryption = PkEncryption(decryption.public_key)
-        message = encryption.encrypt(bytes([0xed]))
+        message = encryption.encrypt(b"\xed")
         plaintext = decryption.decrypt(message)
         assert plaintext == u"�"

python/tests/session_test.py

 # -*- coding: utf-8 -*-
-from builtins import bytes
-
 import pytest
 
 from olm import (Account, InboundSession, OlmMessage, OlmPreKeyMessage,
@@ -147,7 +145,7 @@ class TestClass(object):
 
     def test_invalid_unicode_decrypt(self):
         alice, bob, session = self._create_session()
-        message = session.encrypt(bytes([0xed]))
+        message = session.encrypt(b"\xed")
 
         bob_session = InboundSession(bob, message)
         plaintext = bob_session.decrypt(message)