chore(core/database): delete useless example binary

crates/core/database/examples/migrate.rs

@@ -1,7 +0,0 @@
-use revolt_database::DatabaseInfo;
-
-#[async_std::main]
-async fn main() {
-    let db = DatabaseInfo::Auto.connect().await.unwrap();
-    db.migrate_database().await.unwrap();
-}