fix: remove hardcoded GCP project ID

[Samybty]

Problem

The Taskfile.yml in 03-installation-and-setup directory used a hardcoded GCP project ID in the Workload Identity configuration:

--workload-pool=kubernetes-course-424917.svc.id.goog

This only works for the original project.

When another user runs the task with their own GCP project, the cluster creation fails with an error similar to:

Currently, the only supported value for workload pool is ".svc.id.goog"

This error can be confusing, especially for beginners who are not familiar with YAML, Go Task, or GCP configuration.

Solution

This PR dynamically retrieves the currently configured GCP project ID:

vars:
GCP_PROJECT_ID:
sh: gcloud config get-value project 2>/dev/null

The cluster creation command then uses this variable:

--workload-pool={{.GCP_PROJECT_ID}}.svc.id.goog
Result

Each user can now create the cluster in their own GCP project without manually editing the Taskfile.yml.

This makes the configuration:

easier for beginners;
reusable with any GCP project;
less likely to fail because of a hardcoded project ID.
Testing

The following task now uses the active GCP project automatically:

task gcp:06-create-cluster