The fn in question now converts ALL warnings to errors

tests/test_demes.py

@@ -3124,7 +3124,7 @@ def test_simultaneous_pulses_warning(self):
         with pytest.warns(UserWarning, match="Multiple pulses.*same.*time"):
             b2.resolve()
 
-    @pytest.mark.filterwarnings("error:Multiple pulses.*same.*time")
+    @pytest.mark.filterwarnings("error")
     def test_unrelated_pulses_no_warning(self):
         b1 = Builder()
         for j in range(4):