Update plotting backend to matplotlylib for matplotlylib test

Author: marthacryan

Diff for: packages/python/plotly/plotly/tests/test_optional/test_utils/test_utils.py

@@ -438,7 +438,7 @@ def test_no_numpy_int_type(self):
     @pytest.mark.matplotlib
     def test_masked_constants_example():
         try:
-            pd.options.plotting.backend = "matplotlib"
+            pd.options.plotting.backend = "matplotylib"
         except Exception:
             pass