chore: make pypi release workflow perform checkout (#3371)

The pypi workflow step is now a separate job, so it doesn't start with
the code checkout
done already. Run the checkout action so it is available so the bazel
upload
command can run.

(cherry picked from commit cf594f7)

Author: rickeylev

.github/workflows/release.yml

@@ -70,6 +70,10 @@ jobs:
     needs: publish_bcr
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+        with:
+          ref: ${{ github.tag_name || github.ref_name }}
       - if: github.event_name == 'push' || github.event.inputs.publish_to_pypi
         env:
           # This special value tells pypi that the user identity is supplied within the token