Security Patch: Updating google-github-actions to use Workload Identity Provider

[wesfloyd]

Per Google's recommendation, the authentication method should be upgraded to Workload Identity Federation:

"Workload Identity Federation is the recommended approach as it obviates the need to export a long-lived Google Cloud service account key .. We recommend using Workload Identity Federation instead as exporting a long-lived Service Account Key JSON credential poses a security risk."

*Note: in addition to the code changes, the GCP account admin will need to follow these pre-requisite steps to configure Workload Identity Provider.

I learned about this potential security issue while working on an Aave DAO grant setting up the deployment scripts to write to multiple clouds. My testing ability for this was limited due to the permission restrictions on forked repos, but should be more straightforward for an Aave GCP account owner.