nostr : pool: always send `RelayPoolNotification::Message` variant
Always send `RelayPoolNotification::Message` variant, also when using a persistent database and event is already stored.
Closes https://github.com/rust-nostr/nostr/issues/476
Signed-off-by: Yuki Kishimoto
https://github.com/rust-nostr/nostr/commit/a578bc8d65ffba36ff7a462f22a2cf0b367c843a