Retrieves the latest cryptocurrency and blockchain news articles from CoinDesk's RSS feed.
Fetches the current RSS feed from CoinDesk, parses it to extract information about
recent articles, and returns a formatted list of news items including titles,
links, publication timestamps, and summary content.
Returns:
str: A formatted string containing multiple news entries separated by '---',
with each entry showing title, URL, publication time, and summary
Raises:
HTTPStatusError: If the RSS feed request fails
Exception: If RSS parsing encounters errors