Replace futures::future::poll_fn -> core::future::poll_fn.

embassy-stm32/src/rng.rs

@@ -1,10 +1,10 @@
 #![macro_use]
 
+use core::future::poll_fn;
 use core::task::Poll;
 
 use embassy_hal_common::{into_ref, PeripheralRef};
 use embassy_sync::waitqueue::AtomicWaker;
-use futures::future::poll_fn;
 use rand_core::{CryptoRng, RngCore};
 
 use crate::{pac, peripherals, Peripheral};