Possible access to dangling pointer in yarpbroker.cpp

[S-Dafarra]

Describe the bug
While reading the code to understand the issue behind #3104, I came across a warning by the Visual Studio static analyzer.

In particular, the following lines

yarp/src/libYARP_manager/src/yarp/manager/yarpbroker.cpp

Lines 566 to 576 in e4762b0

	Bottle msg, response;
	msg.fromString(request);
	ret = port.write(msg, response);
	NetworkBase::disconnect(port.getName(), szport);
	if(!response.size() || !ret) {
	port.close();
	return nullptr;
	}
	port.close();
	return response.toString().c_str();

return a pointer to the char buffer of a temporary string.

Configuration (please complete the following information):

• OS:
• yarp version: 3.9.0
• compiler:

Additional context
Add any other context about the problem here.

cc @randaz81