depend on async-broadcast, 0.6 seems to be unsupported on wasm yet an…

…d requires a PR

smol-rs/async-broadcast#51 would be necessary
for 0.6, but 0.5 seems to build fine, so let's just use it

Cargo.toml

@@ -33,6 +33,7 @@ _tests = [ # internal feature, for use by wasm tests in particular and thus all
 
 [dependencies]
 anyhow = "1.0"
+async-broadcast = "0.5.0"
 async-stream = "0.3.5"
 chrono = "0.4.31"
 deepsize = "0.2.0"