fix: "Plugin Artifact for PR / Comment with Artifact Links" action fails

[ahuseyn]

The GitHub Actions workflow “Plugin Artifact for PR” is failing on PR builds with:

• HttpError: Resource not accessible by integration
• thrown from actions/github-script@v7

Failing job example:
https://github.com/wpengine/hwptoolkit/actions/runs/22554367088/job/65329246766?pr=581

Relevant log excerpt (ref 531ef035904cc713c6854e43a6e7f4c2c54205eb):

• RequestError [HttpError]: Resource not accessible by integration
• Unhandled error: HttpError: Resource not accessible by integration

Expected:
Workflow should complete successfully (or gracefully skip steps) when running for PRs.

Actual:
Job fails when the github-script step tries to access a GitHub API resource that the workflow token can’t access in this context.

Likely cause:
GITHUB_TOKEN permissions are insufficient for the API call being made (common for PRs from forks / read-only token contexts or missing permissions: block).

Acceptance criteria:

• Workflow no longer fails on PR runs.