Removes dateutil.

worlds/shivers/Constants.py

@@ -3,17 +3,23 @@
 import pkgutil
 from datetime import datetime
 
-from dateutil.relativedelta import relativedelta
-
 
 def load_data_file(*args) -> dict:
     fname = os.path.join("data", *args)
     return json.loads(pkgutil.get_data(__name__, fname).decode())
 
 
+def relative_years_from_today(dt2: datetime) -> int:
+    today = datetime.now()
+    years = today.year - dt2.year
+    if today.month < dt2.month or (today.month == dt2.month and today.day < dt2.day):
+        years -= 1
+    return years
+
+
 location_id_offset: int = 27000
 location_info = load_data_file("locations.json")
 location_name_to_id = {name: location_id_offset + index for index, name in enumerate(location_info["all_locations"])}
 exclusion_info = load_data_file("excluded_locations.json")
 region_info = load_data_file("regions.json")
-years_since_sep_30_1980 = relativedelta(datetime.now(), datetime.fromisoformat("1980-09-30")).years
+years_since_sep_30_1980 = relative_years_from_today(datetime.fromisoformat("1980-09-30"))