Update test_cellstotex.py

expected failure

Author: mmatera

test/test_cellstotex.py

@@ -5,6 +5,7 @@
 from mathics.core.expression import Symbol
 import pytest
 import urllib.request
+import unittest
 
 external_url = (
     "https://raw.githubusercontent.com/jkuczm/MathematicaCellsToTeX/master/NoInstall.m"
@@ -55,6 +56,7 @@ def test_load():
 #@pytest.mark.skip(
 #    reason="FIXME: full CellToTeX import test is not working yet: implement levelspec > 1"
 #)
+@unittest.expectedFailure
 def test_load_and_run():
     print("load and run")
     str_expected0 = "None"