Adding depracated warning for units M and Y

ryankarlos · ryankarlos · commit 894f9bbbb265 · 2018-11-12T20:26:32.000Z
diff --git a/pandas/core/tools/timedeltas.py b/pandas/core/tools/timedeltas.py
@@ -10,6 +10,7 @@
 
 from pandas.core.dtypes.common import is_list_like
 from pandas.core.dtypes.generic import ABCSeries, ABCIndexClass
+import warnings
 
 from pandas.core.arrays.timedeltas import sequence_to_td64ns
 
