Upgrade tokio to 1.22.0 and replace async-std with tokio (#1917)

* Make tokio executor mandatory

* kick CI

* Update Cargo.lock

cumulus/client/relay-chain-minimal-node/src/network.rs

@@ -72,9 +72,9 @@ pub(crate) fn build_collator_network(
 		role: config.role.clone(),
 		executor: {
 			let spawn_handle = Clone::clone(&spawn_handle);
-			Some(Box::new(move |fut| {
+			Box::new(move |fut| {
 				spawn_handle.spawn("libp2p-node", Some("networking"), fut);
-			}))
+			})
 		},
 		fork_id: None,
 		chain_sync: Box::new(chain_sync),