[ rust-nostr/nostr ] memory: support NIP-62

Pull-Request: https://github.com/rust-nostr/nostr/pull/1272
Signed-off-by: Yuki Kishimoto <yukikishimoto@protonmail.com>
https://github.com/rust-nostr/nostr/commit/860e239ff894b8471b37c84dcac12b9572b8f064