Use tomb v2, update deps, fix hang on stale connection

- Use tomb v2 to properly spawn and reap goroutines (hopefully)
- Update deps
- Fix hang on stale connection due to improper goroutine management

vendor/golang.org/x/sys/windows/syscall.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build windows
-// +build windows
 
 // Package windows contains an interface to the low-level operating system
 // primitives. OS details vary depending on the underlying system, and