go.mod: update golang.org/x dependencies

Update golang.org/x dependencies to their latest tagged versions.

Change-Id: I45df4f6fb03e90e5ba74d97e35eae79009737039
Reviewed-on: https://go-review.googlesource.com/c/debug/+/568777
Auto-Submit: Gopher Robot <gobot@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
diff --git a/go.mod b/go.mod
index 96e09c2..8634cdf 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
 	github.com/spf13/cobra v0.0.3
 	github.com/spf13/pflag v1.0.3
-	golang.org/x/sys v0.17.0
+	golang.org/x/sys v0.18.0
 )
 
 require (
diff --git a/go.sum b/go.sum
index 84fa8b1..81d3429 100644
--- a/go.sum
+++ b/go.sum
@@ -10,5 +10,5 @@
 github.com/spf13/cobra v0.0.3/go.mod h1:1l0Ry5zgKvJasoi3XT1TypsSe7PqH0Sj9dhYf7v3XqQ=
 github.com/spf13/pflag v1.0.3 h1:zPAT6CGy6wXeQ7NtTnaTerfKOsV6V6F8agHXFiazDkg=
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
-golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
-golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.18.0 h1:DBdB3niSjOA/O0blCZBqDefyWNYveAYMNF1Wum0DYQ4=
+golang.org/x/sys v0.18.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=