Handle 404

[eteubert]

The following error occurred. An error tuple is returned but only ok is expected. Error must be handled as well.

[error] Process #PID<0.660.0> raised an exception
** (CaseClauseError) no case clause matching: {:error, 404}
    (metalove 0.4.0) lib/metalove/enclosure.ex:64: Metalove.Enclosure.fetch_and_parse_metadata_p/2
    (metalove 0.4.0) lib/metalove/enclosure.ex:51: Metalove.Enclosure.fetch_metadata/1
    (metalove 0.4.0) lib/metalove/podcast_feed.ex:255: anonymous fn/1 in Metalove.PodcastFeed.scrape_episode_metadata/1
    (elixir 1.15.7) lib/enum.ex:984: Enum."-each/2-lists^foreach/1-0-"/2