Ignore buggy clippy::arc_with_non_send_sync lint

```
error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
   --> futures-channel/src/mpsc/mod.rs:348:17
    |
348 |       let inner = Arc::new(BoundedInner {
    |  _________________^
349 | |         buffer,
350 | |         state: AtomicUsize::new(INIT_STATE),
351 | |         message_queue: Queue::new(),
...   |
354 | |         recv_task: AtomicWaker::new(),
355 | |     });
    | |______^
    |
    = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync
    = note: `#[deny(clippy::arc_with_non_send_sync)]` on by default

error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
   --> futures-channel/src/mpsc/mod.rs:379:17
    |
379 |       let inner = Arc::new(UnboundedInner {
    |  _________________^
380 | |         state: AtomicUsize::new(INIT_STATE),
381 | |         message_queue: Queue::new(),
382 | |         num_senders: AtomicUsize::new(1),
383 | |         recv_task: AtomicWaker::new(),
384 | |     });
    | |______^
    |
    = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync

error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
   --> futures-channel/src/oneshot.rs:105:17
    |
105 |     let inner = Arc::new(Inner::new());
    |                 ^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync

error: could not compile `futures-channel` (lib) due to 3 previous errors

error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
   --> futures-util/src/future/future/shared.rs:101:28
    |
101 |         Self { inner: Some(Arc::new(inner)), waker_key: NULL_WAKER_KEY }
    |                            ^^^^^^^^^^^^^^^
    |
    = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync
    = note: `#[deny(clippy::arc_with_non_send_sync)]` on by default

error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
   --> futures-util/src/stream/futures_unordered/mod.rs:131:34
    |
131 |           let ready_to_run_queue = Arc::new(ReadyToRunQueue {
    |  __________________________________^
132 | |             waker: AtomicWaker::new(),
133 | |             head: AtomicPtr::new(stub_ptr as *mut _),
134 | |             tail: UnsafeCell::new(stub_ptr),
135 | |             stub,
136 | |         });
    | |__________^
    |
    = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync

error: usage of `Arc<T>` where `T` is not `Send` or `Sync`
  --> futures-util/src/lock/bilock.rs:64:19
   |
64 |           let arc = Arc::new(Inner {
   |  ___________________^
65 | |             state: AtomicPtr::new(ptr::null_mut()),
66 | |             value: Some(UnsafeCell::new(t)),
67 | |         });
   | |__________^
   |
   = help: consider using `Rc<T>` instead or wrapping `T` in a std::sync type like `Mutex<T>`
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#arc_with_non_send_sync
```

Author: taiki-e

futures-channel/src/lib.rs

@@ -26,6 +26,7 @@
         allow(dead_code, unused_assignments, unused_variables)
     )
 ))]
+#![allow(clippy::arc_with_non_send_sync)] // false positive https://github.com/rust-lang/rust-clippy/issues/11076
 
 #[cfg(not(futures_no_atomic_cas))]
 #[cfg(feature = "alloc")]

futures-util/src/lib.rs

@@ -19,6 +19,7 @@
 ))]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 #![allow(clippy::needless_borrow)] // https://github.com/rust-lang/futures-rs/pull/2558#issuecomment-1030745203
+#![allow(clippy::arc_with_non_send_sync)] // false positive https://github.com/rust-lang/rust-clippy/issues/11076
 
 #[cfg(all(feature = "bilock", not(feature = "unstable")))]
 compile_error!("The `bilock` feature requires the `unstable` feature as an explicit opt-in to unstable features");