workflows: update pr-auditor workflow (#199)

Author: bobheadxi

.github/workflows/pr-auditor.yml

@@ -1,19 +1,20 @@
+# See https://docs.sourcegraph.com/dev/background-information/ci#pr-auditor
 name: pr-auditor
 on:
-  pull_request:
-    types: [ closed, edited, opened ]
+  pull_request_target:
+    types: [ closed, edited, opened, synchronize, ready_for_review ]
 
 jobs:
-  run:
+  check-pr:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
         with: { repository: 'sourcegraph/sourcegraph' }
       - uses: actions/setup-go@v2
-        with: { go-version: '1.17' }
+        with: { go-version: '1.18' }
 
       - run: ./dev/pr-auditor/check-pr.sh
         env:
           GITHUB_EVENT_PATH: ${{ env.GITHUB_EVENT_PATH }}
           GITHUB_TOKEN: ${{ secrets.CODENOTIFY_GITHUB_TOKEN }}
-          GITHUB_RUN_URL: https://github.com/sourcegraph/infrastructure/actions/runs/${{ github.run_id }}
+          GITHUB_RUN_URL: https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}