Issue with UDP Port parsing

[SouvickDutta]

When I try to spin up a local forwarder on an UDP port, azbridge starts listening on an incorrect port.
Eg -
sudo azbridge -v -L localhost:123U:endpoint -x "***"

dbug: azbridge[0]
[11/15/2023 12:29:46], RemoteForwardHostStarting, 4cdd7979-ac68-4c32-b83a-2b7619274d03,
info: azbridge[0]
[11/15/2023 12:29:46], RemoteForwardHostStart, 4cdd7979-ac68-4c32-b83a-2b7619274d03,
dbug: azbridge[0]
[11/15/2023 12:29:46], LocalForwardHostStarting, feacf8b6-00f7-4db9-ba7f-b979c9d64722,
dbug: azbridge[0]
[11/15/2023 12:29:46], LocalForwardBridgeStarting, 826dbead-5c34-4668-9589-875eaa2b92fc, { localForward = Microsoft.Azure.Relay.Bridge.Configuration.LocalForward }
dbug: azbridge[0]
[11/15/2023 12:29:46], LocalForwardListenerStarting, 1b043cc6-83f0-4c1e-b95a-e4191b40dfbe, { listenEndpoint = 127.0.0.1:12 }
info: azbridge[0]
[11/15/2023 12:29:46], LocalForwardListenerStart, 1b043cc6-83f0-4c1e-b95a-e4191b40dfbe, { localEndpoint = 127.0.0.1:12 }
info: azbridge[0]
[11/15/2023 12:29:46], LocalForwardBridgeStart, 826dbead-5c34-4668-9589-875eaa2b92fc, { bindToAddress = 127.0.0.1, localForward = Microsoft.Azure.Relay.Bridge.Configuration.LocalForward}
info: azbridge[0]
[11/15/2023 12:29:46], LocalForwardHostStart, feacf8b6-00f7-4db9-ba7f-b979c9d64722,
Press Ctrl+C to

azure-relay-bridge/src/Microsoft.Azure.Relay.Bridge/Configuration/Config.cs

Line 619 in d630d51

portString = "-" + portString.Substring(0, portString.Length - 2);

The value of the second argument passed to Substring seems incorrect. It should be portString.Length - 1