fix the wokflow file

Author: ngeojiajun-deriv

.github/workflows/merged.yml

@@ -8,7 +8,7 @@ on:
       - perl_40
 
 env:
-  BRANCH_NAME: ${{ github.ref_name == "master" && 'latest' :  github.ref_name }}
+  BRANCH_NAME: ${{ github.ref_name == "master" && 'latest' ||  github.ref_name }}
 
 jobs:
   perl:
@@ -43,6 +43,11 @@ jobs:
         with:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
+      -
+        name: Pull the associated perl image
+        run: |
+          docker pull deriv/perl:${{env.BRANCH_NAME}}
+          docker tag deriv/perl:${{env.BRANCH_NAME}} deriv/perl:latest
       -
         name: Build And Publish Docker Image
         uses: docker/build-push-action@0565240e2d4ab88bba5387d719585280857ece09