Bump actions/setup-go from 2 to 3

Bumps [actions/setup-go](https://github.com/actions/setup-go) from 2 to 3.
- [Release notes](https://github.com/actions/setup-go/releases)
- [Commits](actions/setup-go@v2...v3)

---
updated-dependencies:
- dependency-name: actions/setup-go
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/pr-auditor.yml

@@ -9,7 +9,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
         with: { repository: 'sourcegraph/sourcegraph' }
-      - uses: actions/setup-go@v2
+      - uses: actions/setup-go@v3
         with: { go-version: '1.17' }
 
       - run: ./dev/pr-auditor/check-pr.sh