Fix release detection step

Author: jovial

.github/workflows/overcloud-host-image-promote.yml

@@ -44,6 +44,7 @@ jobs:
         run: |
           BRANCH=$(awk -F'=' '/defaultbranch/ {print $2}' .gitreview)
           echo "openstack_release=${BRANCH}" | sed "s|stable/||" >> $GITHUB_OUTPUT
+        working-directory: src/kayobe-config
 
       - name: Clone StackHPC Kayobe repository
         uses: actions/checkout@v4