[actions] update checkout action

Author: ljharb

.github/workflows/rebase.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - uses: ljharb/rebase@master
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}