all: update go directive to 1.18

Done with:

go get go@1.18
go mod tidy
go fix ./...

Using go1.21.3.

For golang/go#60268.

Change-Id: Ic6a53c8e217966f5f95b3a968b25ef123b4b99cf
Reviewed-on: https://go-review.googlesource.com/c/term/+/534475
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
diff --git a/go.mod b/go.mod
index 30adbb4..2d0afe5 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,5 @@
 module golang.org/x/term
 
-go 1.17
+go 1.18
 
 require golang.org/x/sys v0.13.0
diff --git a/term_unix.go b/term_unix.go
index 62c2b3f..1ad0ddf 100644
--- a/term_unix.go
+++ b/term_unix.go
@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
-// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris zos
 
 package term
 
diff --git a/term_unix_bsd.go b/term_unix_bsd.go
index 853b3d6..9dbf546 100644
--- a/term_unix_bsd.go
+++ b/term_unix_bsd.go
@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build darwin || dragonfly || freebsd || netbsd || openbsd
-// +build darwin dragonfly freebsd netbsd openbsd
 
 package term
 
diff --git a/term_unix_other.go b/term_unix_other.go
index 1e8955c..1b36de7 100644
--- a/term_unix_other.go
+++ b/term_unix_other.go
@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build aix || linux || solaris || zos
-// +build aix linux solaris zos
 
 package term
 
diff --git a/term_unsupported.go b/term_unsupported.go
index f1df850..3c409e5 100644
--- a/term_unsupported.go
+++ b/term_unsupported.go
@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !zos && !windows && !solaris && !plan9
-// +build !aix,!darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!zos,!windows,!solaris,!plan9
 
 package term