fix: fix mod.ts to export new features of v1.1.0

Author: lambdalisue

mod.ts

@@ -1,8 +1,11 @@
 export * from "./async_value.ts";
 export * from "./barrier.ts";
+export * from "./ensure_promise.ts";
+export * from "./flush_promises.ts";
 export * from "./lock.ts";
 export * from "./mutex.ts";
 export * from "./notify.ts";
+export * from "./peek_promise_state.ts";
 export * from "./promise_state.ts";
 export * from "./queue.ts";
 export * from "./rw_lock.ts";