fake-gcs-server omits the generation field, breaking the official PHP storage client

Uploading a file to fake-gcs-server with the official Google PHP storage client broke because the upload response omitted the generation field entirely. The PHP client's Bucket.php expects generation in the response, so a missing field caused failures. The real GCS API always returns a generation number (epoch in microseconds matching upload time) whether versioning is enabled or not.

The filesystem backend did not serialize a generation field when none was set. The maintainer fixed it in PR #812 so the fake server always returns a generation number (based on the current time), matching the real GCS API, and the reporter confirmed uploads now work with the PHP client. Upgrade fake-gcs-server to a build containing the #812 fix and update the Docker image.

Source: https://github.com/fsouza/fake-gcs-server/issues/701