nostr: fix clippy for MSRV

Signed-off-by: Yuki Kishimoto <[email protected]>

Author: yukibtc

crates/nostr/src/nips/nip47.rs

@@ -725,12 +725,9 @@ impl Response {
                 }
                 Method::ListTransactions => {
                     let transactions: Value =
-                        result
-                            .get("transactions")
-                            .cloned()
-                            .ok_or(Error::UnexpectedResult(String::from(
-                                "Missing 'transactions' field",
-                            )))?;
+                        result.get("transactions").cloned().ok_or_else(|| {
+                            Error::UnexpectedResult(String::from("Missing 'transactions' field"))
+                        })?;
                     let result: Vec<LookupInvoiceResponseResult> =
                         serde_json::from_value(transactions)?;
                     ResponseResult::ListTransactions(result)