Another CD fix: repo not checked out during publish (#2119)

.github/workflows/cd_release.yml

@@ -116,6 +116,13 @@ jobs:
     - name: Install prerequisites
       run: python -m pip install build
 
+    - name: Checkout repository
+      uses: actions/checkout@v4
+      with:
+        submodules: true
+        fetch-depth: 0
+        ref: ${{ needs.release.outputs.publish_branch }}
+
     - name: Build source distribution
       run: python -m build