relax unpin bounds on payload types (#2545)

actix-http/src/h2/dispatcher.rs

@@ -108,8 +108,8 @@ where
             match Pin::new(&mut this.connection).poll_accept(cx)? {
                 Poll::Ready(Some((req, tx))) => {
                     let (parts, body) = req.into_parts();
-                    let pl = crate::h2::Payload::new(body);
-                    let pl = Payload::H2(pl);
+                    let payload = crate::h2::Payload::new(body);
+                    let pl = Payload::H2 { payload };
                     let mut req = Request::with_payload(pl);
 
                     let head = req.head_mut();

actix-http/src/h2/mod.rs

@@ -98,3 +98,14 @@ where
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::panic::{RefUnwindSafe, UnwindSafe};
+
+    use static_assertions::assert_impl_all;
+
+    use super::*;
+
+    assert_impl_all!(Payload: Unpin, Send, Sync, UnwindSafe, RefUnwindSafe);
+}