Update to tokio 1.1 (#2172)

## Issue Addressed

resolves #2129
resolves #2099 
addresses some of #1712
unblocks #2076
unblocks #2153 

## Proposed Changes

- Updates all the dependencies mentioned in #2129, except for web3. They haven't merged their tokio 1.0 update because they are waiting on some dependencies of their own. Since we only use web3 in tests, I think updating it in a separate issue is fine. If they are able to merge soon though, I can update in this PR. 

- Updates `tokio_util` to 0.6.2 and `bytes` to 1.0.1.

- We haven't made a discv5 release since merging tokio 1.0 updates so I'm using a commit rather than release atm. **Edit:** I think we should merge an update of `tokio_util` to 0.6.2 into discv5 before this release because it has panic fixes in `DelayQueue`  --> PR in discv5:  https://github.com/sigp/discv5/pull/58

## Additional Info

tokio 1.0 changes that required some changes in lighthouse:

- `interval.next().await.is_some()` -> `interval.tick().await`
- `sleep` future is now `!Unpin` -> https://github.com/tokio-rs/tokio/issues/3028
- `try_recv` has been temporarily removed from `mpsc` -> https://github.com/tokio-rs/tokio/issues/3350
- stream features have moved to `tokio-stream` and `broadcast::Receiver::into_stream()` has been temporarily removed -> `https://github.com/tokio-rs/tokio/issues/2870
- I've copied over the `BroadcastStream` wrapper from this PR, but can update to use `tokio-stream` once it's merged https://github.com/tokio-rs/tokio/pull/3384

Co-authored-by: realbigsean <seananderson33@gmail.com>

beacon_node/eth1/Cargo.toml

@@ -13,7 +13,7 @@ environment = { path = "../../lighthouse/environment" }
 tokio-compat-02 = "0.1"
 
 [dependencies]
-reqwest = { version = "0.10.8", features = ["native-tls-vendored"] }
+reqwest = { version = "0.11.0", features = ["native-tls-vendored"] }
 futures = "0.3.7"
 serde_json = "1.0.58"
 serde = { version = "1.0.116", features = ["derive"] }
@@ -26,7 +26,7 @@ tree_hash = "0.1.1"
 eth2_hashing = "0.1.0"
 parking_lot = "0.11.0"
 slog = "2.5.2"
-tokio = { version = "0.3.2", features = ["full"] }
+tokio = { version = "1.1.0", features = ["full"] }
 state_processing = { path = "../../consensus/state_processing" }
 libflate = "1.0.2"
 lighthouse_metrics = { path = "../../common/lighthouse_metrics"}

beacon_node/eth1/src/service.rs

@@ -9,7 +9,7 @@ use crate::{
     inner::{DepositUpdater, Inner},
 };
 use fallback::{Fallback, FallbackError};
-use futures::{future::TryFutureExt, StreamExt};
+use futures::future::TryFutureExt;
 use parking_lot::{RwLock, RwLockReadGuard};
 use serde::{Deserialize, Serialize};
 use slog::{crit, debug, error, info, trace, warn, Logger};
@@ -721,7 +721,8 @@ impl Service {
         let mut interval = interval_at(Instant::now(), update_interval);
 
         let update_future = async move {
-            while interval.next().await.is_some() {
+            loop {
+                interval.tick().await;
                 self.do_update(update_interval).await.ok();
             }
         };