Fix last use of assertDictContainsSubset

The method was deprecated in Python 3.2 [1]; and
no longer available in Python version 3.12 [2]

assertLessEqual [3] offers a decent alternative.
Much of this work was done in
I74276297d80cbd055a9347b0d595fe7c2d7742cc. One
last occurrence remained.

[1] https://docs.python.org/3/whatsnew/3.2.html#unittest
[2] https://docs.python.org/3/whatsnew/3.12.html#id3
[3] https://docs.python.org/3/library/unittest.html#unittest.TestCase.assertLessEqual

Change-Id: I2f32f9815196a4d627ce22b382cdcb1f49027a52
Closes-Bug: #2085467
Signed-off-by: Goutham Pacha Ravi <gouthampravi@gmail.com>
diff --git a/manila_tempest_tests/tests/api/test_share_network_subnets.py b/manila_tempest_tests/tests/api/test_share_network_subnets.py
index ec5c79e..09f903c 100644
--- a/manila_tempest_tests/tests/api/test_share_network_subnets.py
+++ b/manila_tempest_tests/tests/api/test_share_network_subnets.py
@@ -175,7 +175,7 @@
         # Default subnet was created during share network creation
         self.assertIsNone(default_subnet['availability_zone'])
         # Match new subnet content
-        self.assertDictContainsSubset(data, subnet)
+        self.assertLessEqual(data.items(), subnet.items())
         # Match share server subnet
         if check_multiple_subnet:
             self.assertIn(subnet['id'],