Simplify process_swap_request (#631)

* Simplify process_swap_request

* Fix occasional test_swap_to_send wallet errors

crates/cdk-sqlite/src/wallet/memory.rs

@@ -6,7 +6,11 @@ use super::WalletSqliteDatabase;
 
 /// Creates a new in-memory [`WalletSqliteDatabase`] instance
 pub async fn empty() -> Result<WalletSqliteDatabase, Error> {
-    let db = WalletSqliteDatabase::new(":memory:").await?;
+    let db = WalletSqliteDatabase {
+        pool: sqlx::sqlite::SqlitePool::connect(":memory:")
+            .await
+            .map_err(|e| Error::Database(Box::new(e)))?,
+    };
     db.migrate().await;
     Ok(db)
 }