fix(transport): libp2p compilation in Nim version-2-0 and devel (#1186)

For example:
```
/Users/runner/work/nim-libp2p/nim-libp2p/nimbledeps/pkgs2/websock-0.1.0-94f836ae589056b2deb04bdfdcd614fff80adaf5/websock/http/client.nim(173, 5) template/generic instantiation of `async` from here
/Users/runner/work/nim-libp2p/nim-libp2p/nimbledeps/pkgs2/websock-0.1.0-94f836ae589056b2deb04bdfdcd614fff80adaf5/websock/http/client.nim(165, 1) Warning: The raises pragma doesn't work on async procedures - use `async: (raises: [...]) instead. [User]
/Users/runner/work/nim-libp2p/nim-libp2p/nimbledeps/pkgs2/websock-0.1.0-94f836ae589056b2deb04bdfdcd614fff80adaf5/websock/websock.nim(257, 5) template/generic instantiation of `async` from here
/Users/runner/work/nim-libp2p/nim-libp2p/nimbledeps/pkgs2/websock-0.1.0-94f836ae589056b2deb04bdfdcd614fff80adaf5/websock/websock.nim(251, 1) Warning: The raises pragma doesn't work on async procedures - use `async: (raises: [...]) instead. [User]
/Users/runner/work/nim-libp2p/nim-libp2p/libp2p/transports/wstransport.nim(77, 18) template/generic instantiation of `async` from here
/Users/runner/work/nim-libp2p/nim-libp2p/libp2p/transports/wstransport.nim(83, 10) template/generic instantiation of `setResult` from here
/Users/runner/work/nim-libp2p/nim-libp2p/libp2p/transports/wstransport.nim(78, 26) template/generic instantiation of `mapExceptions` from here
/Users/runner/work/nim-libp2p/nim-libp2p/nimbledeps/pkgs2/chronos-4.0.2-c5e9517b9189713210e2abab8b77a68da71ded12/chronos/internal/asyncmacro.nim(542, 60) Error: expression 'value(cast[type(recv(s.session, pbytes, nbytes))](chronosInternalRetFuture.internalChild))' is of type 'int' and has to be used (or discarded); start of expression here: /Users/runner/work/nim-libp2p/nim-libp2p/libp2p/transports/wstransport.nim(78, 26)
stack trace: (most recent call last)
```
from
https://github.com/vacp2p/nim-libp2p/actions/runs/10655841970/job/29533846606?pr=1145

For minimal example of this:
```nim
template g(body: untyped) =
  try:
    body
  except CatchableError:
    raise newException(CatchableError, "")

discard g(0)
```

Also, even in 2.0.8, a variation doesn't work:
```
template g(body: untyped) = body
discard g(0)
```

libp2p/transports/wstransport.nim

@@ -56,7 +56,7 @@ proc new*(
   stream.initStream()
   return stream
 
-template mapExceptions(body: untyped) =
+template mapExceptions(body: untyped): untyped =
   try:
     body
   except AsyncStreamIncompleteError: