Build artifacts inaccessible

[againull]

It seems like build artifacts have become inaccessible.

Clicking status of Linux GCC build in
https://github.com/KhronosGroup/SPIRV-Tools/blob/main/docs/downloads.md results in:

<Error>
<Code>AccessDenied</Code>
<Message>Access denied.</Message>
<Details>Anonymous caller does not have storage.objects.get access to the Google Cloud Storage object. Permission 'storage.objects.get' denied on resource (or it may not exist).</Details>
</Error>