nx-cugraph: xfail test_louvain.py:test_threshold in Python 3.9 (#3944)

This test is flaky b/c Louvain in PLC does not have a seed or random state parameter. This test holds the seed fixed and changes the threshold, but clearly this may not work if we can't set the seed.

Authors:
  - Erik Welch (https://github.com/eriknw)

Approvers:
  - Rick Ratzel (https://github.com/rlratzel)
  - Naim (https://github.com/naimnv)

URL: #3944

python/nx-cugraph/nx_cugraph/interface.py

@@ -12,6 +12,8 @@
 # limitations under the License.
 from __future__ import annotations
 
+import sys
+
 import networkx as nx
 
 import nx_cugraph as nxcg
@@ -180,6 +182,11 @@ def key(testpath):
                     ): "self-loops not handled in Louvain",
                 }
             )
+            if sys.version_info[:2] == (3, 9):
+                # This test is sensitive to RNG, which depends on Python version
+                xfail[
+                    key("test_louvain.py:test_threshold")
+                ] = "Louvain does not support seed parameter"
 
         for item in items:
             kset = set(item.keywords)