Update get_top_billionaires.py to fix doctest failure

web_programming/get_top_billionaires.py

@@ -29,7 +29,7 @@ def calculate_age(unix_date: float) -> str:
     >>> from datetime import datetime, UTC
     >>> years_since_create = datetime.now(tz=UTC).year - 2022
     >>> int(calculate_age(-657244800000)) - years_since_create
-    73
+    72
     >>> int(calculate_age(46915200000)) - years_since_create
     51
     """