Fix JET errors around matching methods for send_msg(...) (#166)

```
┌ send_msg(s::IO, header::Any, msg::Any) @ Distributed /workpath/Distributed.jl/src/messages.jl:105
│ no matching method found `send_msg(::Distributed.LocalProcess, ::Any, ::Any)` (1/2 union split): Distributed.send_msg(Distributed.worker_from_id(id::Int64)::Union{Distributed.LocalProcess, Distributed.Worker}, header::Any, msg::Any)
└────────────────────
```

(cherry picked from commit 7223f4f14dc3749515ae36e76973045e27791606)
(cherry picked from commit 56fa9f214afd5f2c487ac4132aee8e50daf19c0e)

Author: DilumAluthge

src/messages.jl

@@ -102,7 +102,7 @@ end
 function send_msg(s::IO, header, msg)
     id = worker_id_from_socket(s)
     if id > -1
-        return send_msg(worker_from_id(id), header, msg)
+        return send_msg(worker_from_id(id)::Worker, header, msg)
     end
     send_msg_unknown(s, header, msg)
 end