batch changes - update checkout v2 to v3 (#160)

Co-authored-by: Sourcegraph <[email protected]>

Author: daxmc99

.github/workflows/pr-auditor.yml

@@ -8,7 +8,7 @@ jobs:
   check-pr:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with: { repository: 'sourcegraph/sourcegraph' }
       - uses: actions/setup-go@v2
         with: { go-version: '1.18' }