Using event.release.target_commitish for target branch

Can use this.
Or can set it to use the default branch always since the releases would only be triggered on changes to master branch.

.github/workflows/image_build_push.yml

@@ -74,9 +74,11 @@ jobs:
         id: get-branch-name
         run: |
           if [ "${{ github.ref_type }}" == "tag" ]; then
-            base_ref=${{ github.event.base_ref }}
-            echo "Branch name: branch_name=${base_ref#refs/heads/}"
-            echo "branch_name=${base_ref#refs/heads/}" >> "$GITHUB_OUTPUT"
+            # base_ref=${{ github.event.base_ref }}
+            # echo "Branch name: branch_name=${base_ref#refs/heads/}"
+            # echo "branch_name=${base_ref#refs/heads/}" >> "$GITHUB_OUTPUT"
+            target_branch=${{ github.event.release.target_commitish }}
+            echo "branch_name=${target_branch}" >> "$GITHUB_OUTPUT"
           elif [ "${{ github.ref_type }}" == "branch" ]; then
             echo "branch_name=${GITHUB_REF##*/}" >> "$GITHUB_OUTPUT"    
           fi