PYTHON-4361 Skip transactions tests on MMAPv1 (#1583)

Author: ShaneHarvey

test/test_transactions_unified.py

@@ -20,9 +20,15 @@
 
 sys.path[0:0] = [""]
 
-from test import unittest
+from test import client_context, unittest
 from test.unified_format import generate_test_classes
 
+
+@client_context.require_no_mmap
+def setUpModule():
+    pass
+
+
 # Location of JSON test specifications.
 TEST_PATH = os.path.join(os.path.dirname(os.path.realpath(__file__)), "transactions", "unified")