all: upgrade go directive to at least 1.23.0 [generated]

By now Go 1.24.0 has been released, and Go 1.22 is no longer supported
per the Go Release Policy (https://go.dev/doc/devel/release#policy).

For golang/go#69095.

[git-generate]
(cd . && go get go@1.23.0 && go mod tidy && go fix ./... && go mod edit -toolchain=none)

Change-Id: I718ce0afa60729aeb89396db2b559faf03b90a68
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/649795
Auto-Submit: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

go.mod

@@ -1,6 +1,6 @@
 module golang.org/x/oauth2
 
-go 1.18
+go 1.23.0
 
 require (
 	cloud.google.com/go/compute/metadata v0.3.0