nimsuggest: fix tcp socket leak (#12377) [backport]

A new socket is created for each iteration and leak immediately thanks
to the accept() call replacing the created socket with the client socket.

This commit fixes that.

(cherry picked from commit e9fa4c9b9c)

nimsuggest/nimsuggest.nim

@@ -319,8 +319,8 @@ proc replTcp(x: ThreadParams) {.thread.} =
     server.bindAddr(x.port, x.address)
     server.listen()
   var inp = "".TaintedString
+  var stdoutSocket: Socket
   while true:
-    var stdoutSocket = newSocket()
     accept(server, stdoutSocket)
 
     stdoutSocket.readLine(inp)