chore(ci): checkout files when updating package-lock (#28778)

In #28697 I moved the
package-lock work to its own step to lets us re-run that if it fails.
However, I forgot to checkout the project files in that step, so there
was no `package-lock.json` file to update [resulting in an
error](https://github.com/ionic-team/ionic-framework/actions/runs/7398703880/job/20128761433).

.github/workflows/release.yml

@@ -78,6 +78,7 @@ jobs:
     needs: [finalize-release]
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v3
       # Lerna does not automatically bump versions
       # of Ionic dependencies that have changed,
       # so we do that here.