Don't default to use async/await on wasm32

We don't automatically want to make the interface `async` based on the
used architecture, but now require the user to explicitly set the
`async-interface` feature.

.github/workflows/cont_integration.yml

@@ -154,7 +154,7 @@ jobs:
       - name: Update toolchain
         run: rustup update
       - name: Check
-        run: cargo check --target wasm32-unknown-unknown --features use-esplora-async,dev-getrandom-wasm --no-default-features
+        run: cargo check --target wasm32-unknown-unknown --features async-interface,use-esplora-async,dev-getrandom-wasm --no-default-features
 
   fmt:
     name: Rust fmt