ci: test more things with miri (#6885)

tokio-util/tests/spawn_pinned.rs

@@ -1,5 +1,7 @@
 #![warn(rust_2018_idioms)]
 #![cfg(not(target_os = "wasi"))] // Wasi doesn't support threads
+// Blocked on https://github.com/rust-lang/miri/issues/3911
+#![cfg(not(miri))]
 
 use std::rc::Rc;
 use std::sync::Arc;

tokio-util/tests/time_delay_queue.rs

@@ -92,6 +92,7 @@ async fn single_short_delay() {
 }
 
 #[tokio::test]
+#[cfg_attr(miri, ignore)] // Too slow on miri.
 async fn multi_delay_at_start() {
     time::pause();
 

tokio-util/tests/udp.rs

@@ -1,5 +1,6 @@
 #![warn(rust_2018_idioms)]
 #![cfg(not(target_os = "wasi"))] // Wasi doesn't support UDP
+#![cfg(not(miri))] // No `socket` in Miri.
 
 use tokio::net::UdpSocket;
 use tokio_stream::StreamExt;