transport/tnet: update tnet dependency

[Rememorio]

What

• Update trpc.group/trpc-go/tnet to v1.1.0.
• Pick up the public tnet restart-related release and its required public dependencies.
• Update the tnet multiplex test fake to satisfy the current tnet.Conn interface.

Compatibility

This keeps trpc-go's existing server-level graceful restart flow unchanged. The new tnet release exposes restart support as an optional interface, but trpc-go still needs to coordinate restart at the whole server process level so mixed transports and multi-service processes keep their current behavior.

Tests

• go test ./... -count=1
• go test ./transport/tnet/multiplex -count=1
• go test ./transport/tnet -count=1
• go test ./transport ./server ./http -count=1

[WineChord]

LGTM