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/unix/ptrace_ios.go

@@ -3,16 +3,9 @@
 // license that can be found in the LICENSE file.
 
 //go:build ios
-// +build ios
 
 package unix
 
-import "unsafe"
-
 func ptrace(request int, pid int, addr uintptr, data uintptr) (err error) {
 	return ENOTSUP
 }
-
-func ptracePtr(request int, pid int, addr uintptr, data unsafe.Pointer) (err error) {
-	return ENOTSUP
-}