Add handling for leap day birthdays

We've been getting a ValueError for day out of range errors when a leap day birthday is entered in a non-leap year. This handles that error.

retirement_api/utils/ss_utilities.py

@@ -98,7 +98,12 @@ def get_months_past_birthday(dob):
 def get_months_until_next_birthday(dob):
     """return number of months until next birthday, with a minimum of 1 """
     today = datetime.date.today()
-    bday_this_year = datetime.date(today.year, dob.month, dob.day)
+    try:
+        bday_this_year = datetime.date(today.year, dob.month, dob.day)
+    except ValueError:
+        # Handle Leap Day birthdays
+        bday_this_year = datetime.date(today.year, dob.month, dob.day - 1)
+
     if today >= bday_this_year:
         return (12 - today.month) + dob.month
     elif today < bday_this_year: