build: Authenticate to Google Cloud

[usmansaleem]

PR Description

build: Authenticate to Google Cloud in CI to enable Google Secrets Manager Acceptance Tests.

Fixed Issue(s)

Documentation

• I thought about documentation and added the doc-change-required label to this PR if updates are required.

Changelog

• I thought about adding a changelog entry, and added one if I deemed necessary.

Testing

• I thought about testing these changes in a realistic/non-local environment.

PR Overview

This PR adds authentication to Google Cloud in CI to enable Google Secrets Manager Acceptance Tests. Key changes include updating the CI workflow to authenticate to Google Cloud and modifying tag filtering and environment variable regex validation for acceptance tests.

• Updated CI workflow to add Google Cloud authentication step and necessary permissions.
• Modified GitHub Actions tag pattern and environment variable regex to enforce non-empty GCP_PROJECT_ID.

Reviewed Changes

File	Description
.github/workflows/ci_main.yml	Added Google Cloud authentication step and updated tag filtering and permissions
acceptance-tests/src/test/java/tech/pegasys/web3signer/tests/bulkloading/GcpSecretManagerAcceptanceTest.java	Revised regex in environment variable dependency to require non-empty values

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

.github/workflows/ci_main.yml:8

• The tag filter now uses '*' instead of the previous semantic versioning regex. Please confirm that this broader trigger is intentional to ensure that builds are not activated by unintended tags.

      - '*'