App Engine PHP sample uses deprecated runtime (php81) #2181

The App Engine Standard PHP sample currently specifies runtime: php81 in app.yaml.

As of now, php81 is end of support and no longer accepted by App Engine Standard, which causes deployments to fail with the following error:

ERROR: (gcloud.app.deploy) INVALID_ARGUMENT: Error(s) encountered validating runtime. Runtime php81 is end of support and no longer allowed.

To avoid deployment failures for users, especially those following tutorials or labs, I propose updating the runtime to a supported version (e.g. php83, or php82 if preferred).

Proposed change:

• Update appengine/standard/helloworld/app.yamlfromruntime: php81` to a currently supported PHP runtime.

I’m happy to submit a pull request if this change is acceptable.