chore(deps): update actions/checkout action to v3

Author: renovate-bot

.github/workflows/build.yml

@@ -9,7 +9,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Use Node.js
         uses: actions/setup-node@v2
         with:

.github/workflows/pr-auditor.yml

@@ -7,7 +7,7 @@ jobs:
   run:
     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: '1.17' }