Revert "close sockets in example app"

This reverts commit 399ad33c99.

examples/app/app.nim

@@ -232,7 +232,6 @@ proc runApp(serverHostname: string, serverPort: Port, peerId: string,
       let msg = await sock.recv(4)
       echo "received message: ", msg
       await sock.send("pong")
-    sock.close()
 
   else:
     # initiate a new connection
@@ -244,7 +243,6 @@ proc runApp(serverHostname: string, serverPort: Port, peerId: string,
     await sock.send("ping")
     let msg = await sock.recv(4)
     echo "received message: ", msg
-    sock.close()
     
 proc main() =
   if paramCount() < 3 or paramCount() > 4: