[tests/test_montgomery] Fix fold names

tests/test_montgomery.py

@@ -96,14 +96,14 @@ def test_protocol_consistency():
     # Cross-validation fold 0-7
     for k in range(8):
         _check_split(
-            f"fold_{k}.json",
+            f"fold-{k}.json",
             lengths=dict(train=99, validation=25, test=14),
         )
 
     # Cross-validation fold 8-9
     for k in range(8, 10):
         _check_split(
-            f"fold_{k}.json",
+            f"fold-{k}.json",
             lengths=dict(train=100, validation=25, test=13),
         )