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

aurora/info.json

@@ -5,7 +5,7 @@
   "short" : "A full replacement for Red's core Mod cogs.",
   "description" : "Aurora is a fully-featured moderation system. It is heavily inspired by GalacticBot, and is designed to be a more user-friendly alternative to Red's core Mod cogs. This cog stores all of its data in an SQLite database.",
   "end_user_data_statement" : "This cog stores the following information:\n- User IDs of accounts who moderate users or are moderated\n- Guild IDs of guilds with the cog enabled\n- Timestamps of moderations\n- Other information relating to moderations",
-  "requirements": ["humanize", "pytimeparse2"],
+  "requirements": ["humanize"],
   "hidden": false,
   "disabled": false,
   "min_bot_version": "3.5.0",