add logger.

Author: gabrielaznar

climada/util/dates_times.py

@@ -1,8 +1,11 @@
 """
 Define functions to handle dates nad times in climada
 """
+import logging
 import datetime as dt
 
+LOGGER = logging.getLogger(__name__)
+
 def date_to_str(date):
     """ Compute date string in ISO format from input datetime ordinal int.