Fix undefined Reticulum variable reference in Link.py

Resolve Pylance error where "Reticulum" is not defined on line 195.
The variable should be referenced as RNS.Reticulum since only the RNS
module is imported, not the Reticulum class directly.

RNS/Link.py

@@ -31,6 +31,7 @@
 from RNS.Cryptography import X25519PrivateKey, X25519PublicKey, Ed25519PrivateKey, Ed25519PublicKey
 from RNS.Cryptography import Token
 from RNS.Channel import Channel, LinkChannelOutlet
+from RNS import Reticulum
 
 from time import sleep
 from .vendor import umsgpack as umsgpack