[CI] Copilot auto-reviews trigger workflow approval requirement on `pr_review_trigger.yml`

[thisisnic]

When GitHub Copilot automatically reviews a PR, it triggers the "Label when reviewed" workflow (pr_review_trigger.yml), which fires on all pull_request_review events. Because copilot-pull-request-reviewer has authorAssociation: "CONTRIBUTOR" (not "MEMBER" or "COLLABORATOR"), GitHub Actions treats it as an outside collaborator and requires a committer to manually click "Approve and run" before the workflow proceeds.

This is unnecessary friction — the workflow only uploads the event payload for the label bot, and Copilot's COMMENTED review shouldn't trigger label changes anyway.

Proposed fix: Add a condition to skip bot reviews in pr_review_trigger.yml:

jobs:
  label-when-reviewed:
    name: "Label PRs when reviewed"
    if: github.event.review.user.type != 'Bot'
    runs-on: ubuntu-latest

This keeps labeling working as normal for human reviews while preventing the unnecessary approval prompt.