Fix deploy-testing docker image id retrieval

Author: Alenar

.github/workflows/ci.yml

@@ -414,7 +414,7 @@ jobs:
       uses: actions/checkout@v3
 
     - name: Get Docker image id
-      run: echo "DOCKER_IMAGE_ID=${{ github.head_ref || github.ref_name }}-$(echo ${{ github.sha }} | cut -c1-7)" >> $GITHUB_ENV
+      run: echo "DOCKER_IMAGE_ID=${{ github.base_ref }}-$(echo ${{ github.sha }} | cut -c1-7)" >> $GITHUB_ENV
 
     - name: Prepare service account credentials
       run: |