cmd/golangorg: update App Engine runtime to Go 1.22

By now the supported and tested Go versions are Go 1.22 and 1.21.
Update the website deployment to start using the Go 1.22 runtime.
See https://cloud.google.com/appengine/docs/standard/lifecycle/support-schedule#go.

Change-Id: I376e36e8aa0f8128c1bcdce6a199c51f163e9c33
Reviewed-on: https://go-review.googlesource.com/c/website/+/587475
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/cmd/golangorg/app.yaml b/cmd/golangorg/app.yaml
index 2cb30d2..893e275 100644
--- a/cmd/golangorg/app.yaml
+++ b/cmd/golangorg/app.yaml
@@ -2,7 +2,7 @@
 # Do not deploy directly.
 
 service: default
-runtime: go121
+runtime: go122
 main: ./cmd/golangorg
 
 env_variables: