Fix outputs

Signed-off-by: ZePan110 <ze.pan@intel.com>

Author: ZePan110

.github/workflows/pr-image-size.yml

@@ -37,7 +37,7 @@ jobs:
           merged_commit=$(git log -1 --format='%H')
           files=$(git diff --name-status --diff-filter=ARM ${{ github.event.pull_request.base.sha }} ${merged_commit} | awk '{print $2}' | grep -E 'Dockerfile$' || true)
           echo "files<<EOF" >> $GITHUB_OUTPUT
-          echo "$files" >> $GITHUB_OUTPUT
+          echo "$files" | tr '\0' '\n' >> $GITHUB_OUTPUT
           echo "EOF" >> $GITHUB_OUTPUT
 
       - name: Build and check image sizes
@@ -75,4 +75,4 @@ jobs:
             echo "::warning::Image size change: $size_base -> $size_pr MB}' (diff: $diff MB)"
             echo "File $dockerfile resulted in a change in the image size from $size_base -> $size_pr MB" >> GITHUB_STEP_SUMMARY
             docker rmi "$image_base" "$image_pr"
-          done <<< "${{ steps.changed-dockerfiles.outputs.files }}"
+          done < <(echo "${{ steps.changed-dockerfiles.outputs.files }}" | tr '\n' '\0')