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/mmap_nomremap.go

@@ -0,0 +1,13 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix || darwin || dragonfly || freebsd || openbsd || solaris || zos
+
+package unix
+
+var mapper = &mmapper{
+	active: make(map[*byte][]byte),
+	mmap:   mmap,
+	munmap: munmap,
+}