"""Parse data and update the date of the last bump in it.

The function searches for a specific pattern in the input string that represents a date in the format '### HEAD as of DD.MM.YYYY ###'. It then replaces this date with the current date in the same format.

Args:
    data (str): The string to parse and update.

Returns:
    str: The input string with the current date replacing the old date in the specified pattern.
"""
You should write code starting with:
import re
from datetime import datetime

def _update_head_date(data: str) -> str:
    # TODO: Implement this function
    pass

