Update XSRF utility tests for Python 3.8 and newer.
Adjust mocked hmac.new() assertions to expect an explicit MD5
digest algorithm, matching the updated XSRF token implementation.
Preserve verification of the original HMAC-MD5 behavior.
--- ../tests/contrib/test_xsrfutil.py	2026-10-16 17:37:03.788733462 +0300
+++ ../tests/contrib/test_xsrfutil.py	2026-10-16 17:38:23.319999056 +0300
@@ -15,6 +15,7 @@
 """Tests for oauth2client.contrib.xsrfutil."""
 
 import base64
+import hashlib
 import unittest
 
 import mock
@@ -54,7 +55,8 @@
                                             TEST_USER_ID_1,
                                             action_id=TEST_ACTION_ID_1,
                                             when=TEST_TIME)
-            hmac.new.assert_called_once_with(TEST_KEY)
+            hmac.new.assert_called_once_with(
+                TEST_KEY, digestmod=hashlib.md5)
             digester.digest.assert_called_once_with()
 
             expected_digest_calls = [
@@ -87,7 +89,8 @@
                                                 TEST_USER_ID_1,
                                                 action_id=TEST_ACTION_ID_1)
 
-                hmac.new.assert_called_once_with(TEST_KEY)
+                hmac.new.assert_called_once_with(
+                    TEST_KEY, digestmod=hashlib.md5)
                 time.time.assert_called_once_with()
                 digester.digest.assert_called_once_with()