allow path to accept weekday_name as well

Author: mroeschke

pandas/_libs/tslibs/fields.pyx

@@ -100,7 +100,7 @@ def get_date_name_field(ndarray[int64_t] dtindex, object field,
     count = len(dtindex)
     out = np.empty(count, dtype=object)
 
-    if field == 'day_name':
+    if field == 'day_name' or field == 'weekday_name':
         if time_locale is None:
             _dayname = np.array(DAYS_FULL, dtype=np.object_)
         else: