go.mod: update golang.org/x dependencies

Update golang.org/x dependencies to their latest tagged versions.
Once this CL is submitted, and post-submit testing succeeds on all
first-class ports across all supported Go versions, this repository
will be tagged with its next minor version.

Change-Id: I953aeb97bb9ed634f69dc93cf1f21392261c930c
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/516037
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Run-TryBot: Gopher Robot <gobot@golang.org>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Gopher Robot <gobot@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

go.mod

@@ -1,6 +1,6 @@
 module golang.org/x/oauth2
 
-go 1.17
+go 1.18
 
 require (
 	cloud.google.com/go/compute/metadata v0.2.3
@@ -11,6 +11,6 @@ require (
 require (
 	cloud.google.com/go/compute v1.20.1 // indirect
 	github.com/golang/protobuf v1.5.3 // indirect
-	golang.org/x/net v0.12.0 // indirect
+	golang.org/x/net v0.14.0 // indirect
 	google.golang.org/protobuf v1.31.0 // indirect
 )

google/appengine_gen1.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build appengine
-// +build appengine
 
 // This file applies to App Engine first generation runtimes (<= Go 1.9).
 

google/appengine_gen2_flex.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !appengine
-// +build !appengine
 
 // This file applies to App Engine second generation runtimes (>= Go 1.11) and App Engine flexible.
 

internal/client_appengine.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build appengine
-// +build appengine
 
 package internal