Silence unexpected messages in mock server

[hissssst]

Hey, thanks for this great library!

My testing logs are getting flooded by messages like

Error: 16:14:39.389 [error] Patch.Mock.Server Patch.Mock.Server.For.Some.Module received unexpected message in handle_info/2: {:EXIT, #PID<0.11558.0>, :normal}

This PR overrides default handle_info into a handler which does nothing

PS: Minor version bump and publish would be heavily appreciated.