feat(aurora): migrated to Red's builtin timedelta/relativedelta parsing

aurora/utilities/utils.py

@@ -1,8 +1,10 @@
 # pylint: disable=cyclic-import
 import json
+from datetime import datetime
 from datetime import timedelta as td
 from typing import Union
 
+from dateutil.relativedelta import relativedelta as rd
 from discord import Guild, Interaction, Member, SelectOption, User
 from discord.errors import Forbidden, NotFound
 from redbot.core import commands
@@ -283,3 +285,9 @@ def create_pagesize_options() -> list[SelectOption]:
             )
         )
     return options
+
+def timedelta_from_relativedelta(relativedelta: rd) -> td:
+    """Converts a relativedelta object to a timedelta object."""
+    now = datetime.now()
+    then = now - relativedelta
+    return now - then