Vendor dependencies

Let's see how I like this workflow.

vendor/tokio/tests/macros_pin.rs

@@ -0,0 +1,21 @@
+#![cfg(feature = "macros")]
+
+#[cfg(tokio_wasm_not_wasi)]
+use wasm_bindgen_test::wasm_bindgen_test as maybe_tokio_test;
+
+#[cfg(not(tokio_wasm_not_wasi))]
+use tokio::test as maybe_tokio_test;
+
+async fn one() {}
+async fn two() {}
+
+#[maybe_tokio_test]
+async fn multi_pin() {
+    tokio::pin! {
+        let f1 = one();
+        let f2 = two();
+    }
+
+    (&mut f1).await;
+    (&mut f2).await;
+}