upgrade tokio to latest version(v0.3)

examples/game_of_life/Cargo.toml

@@ -7,6 +7,6 @@ publish = false
 
 [dependencies]
 iced = { path = "../..", features = ["canvas", "tokio", "debug"] }
-tokio = { version = "0.2", features = ["blocking"] }
+tokio = { version = "0.3", features = ["sync"] }
 itertools = "0.9"
 rustc-hash = "1.1"

futures/Cargo.toml

@@ -20,9 +20,9 @@ log = "0.4"
 version = "0.3"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies.tokio]
-version = "0.2"
+version = "0.3"
 optional = true
-features = ["rt-core", "rt-threaded", "time", "stream"]
+features = ["rt-multi-thread", "time", "stream"]
 
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies.async-std]
 version = "1.0"

futures/src/executor/tokio.rs

@@ -16,6 +16,7 @@ impl Executor for Tokio {
     }
 
     fn enter<R>(&self, f: impl FnOnce() -> R) -> R {
-        tokio::runtime::Runtime::enter(self, f)
+        let _guard = tokio::runtime::Runtime::enter(self);
+        f()
     }
 }

src/executor.rs

@@ -40,7 +40,8 @@ mod platform {
         }
 
         fn enter<R>(&self, f: impl FnOnce() -> R) -> R {
-            self.0.enter(f)
+            let _guard = self.0.enter();
+            f()
         }
     }
 }