workflows: Update to send version updating PR on 4.0 with using v4.0 branch

Signed-off-by: Hiroshi Hatake <[email protected]>

Author: cosmo0920

.github/workflows/staging-release.yaml

@@ -1049,6 +1049,12 @@ jobs:
       - name: Release 4.0
         if: startsWith(inputs.version, '4.0')
         uses: actions/checkout@v4
+        with:
+          ref: 4.0
+
+      - name: Release 4.1
+        if: startsWith(inputs.version, '4.1')
+        uses: actions/checkout@v4
         with:
           ref: master