fix: fix dns on linux (#336)

* fix: fix dns on linux

* feat: detect run in Github action or not to setup DNS

vendor/github.com/tailscale/netlink/netns_unspecified.go

@@ -0,0 +1,19 @@
+// +build !linux
+
+package netlink
+
+func GetNetNsIdByPid(pid int) (int, error) {
+	return 0, ErrNotImplemented
+}
+
+func SetNetNsIdByPid(pid, nsid int) error {
+	return ErrNotImplemented
+}
+
+func GetNetNsIdByFd(fd int) (int, error) {
+	return 0, ErrNotImplemented
+}
+
+func SetNetNsIdByFd(fd, nsid int) error {
+	return ErrNotImplemented
+}