build: deny async-std and friends

rationale: some crates pull these in as default; hopefully these hints
will require less cleanup-after and Cargo.lock file watching.

deny.toml

@@ -74,10 +74,39 @@ highlight = "all"
 workspace-default-features = "allow"
 external-default-features = "allow"
 allow = []
-deny = []
+
 skip = []
 skip-tree = []
 
+[[bans.deny]]
+# we use tokio, the same rationale applies for async-{io,waker,global-executor,executor,channel,lock}, smol
+# if you find yourself here while adding a dependency, try "default-features = false", ask around on #rust
+name = "async-std"
+
+[[bans.deny]]
+name = "async-io"
+
+[[bans.deny]]
+name = "async-waker"
+
+[[bans.deny]]
+name = "async-global-executor"
+
+[[bans.deny]]
+name = "async-executor"
+
+[[bans.deny]]
+# please use tokio channels or flume for mpmc channel
+# please use tokio-stream if you really must get channels wrapped as streams
+name = "async-channel"
+
+[[bans.deny]]
+# use tokio locking primitives
+name = "async-lock"
+
+[[bans.deny]]
+name = "smol"
+
 # This section is considered when running `cargo deny check sources`.
 # More documentation about the 'sources' section can be found here:
 # https://embarkstudios.github.io/cargo-deny/checks/sources/cfg.html