mod+lncli: remove deprecated package [skip ci]

The use of golang.org/x/crypto/ssh/terminal was marked as deprecated
since that code was moved to its own repo golang.org/x/term.
With this commit we use the new package name directly, which was already
pulled in under its new name anyway.

go.mod

@@ -60,6 +60,7 @@ require (
 	golang.org/x/net v0.0.0-20210913180222-943fd674d43e
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
 	golang.org/x/sys v0.0.0-20210915083310-ed5796bab164 // indirect
+	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1
 	golang.org/x/time v0.0.0-20210220033141-f8bda1e9f3ba
 	google.golang.org/grpc v1.38.0
 	google.golang.org/protobuf v1.26.0