fix: allow backend/frontend Docker builds when main version exists (langflow-ai#12854)

Backend and frontend images (langflowai/langflow-backend and
langflowai/langflow-frontend) are separate from the main image
(langflowai/langflow), so they should not be skipped when the
main version already exists on Docker Hub.

This fixes the issue where backend/frontend builds for 1.9.0
were skipped because the main 1.9.0 image was already published,
preventing these critical images from being available on Docker Hub.

Fixes: Backend and frontend Docker images not published in 1.9.0 release

Author: vjgit96

.github/workflows/docker-build-v2.yml

@@ -137,7 +137,8 @@ jobs:
             echo "Latest main release version: $last_released_version"
           fi
 
-          if [ "$version" = "$last_released_version" ]; then
+          # Skip check only applies to main image, not backend/frontend which are separate images
+          if [ "$version" = "$last_released_version" ] && [[ "${{ inputs.release_type }}" != "main-backend" ]] && [[ "${{ inputs.release_type }}" != "main-frontend" ]]; then
             echo "Main docker version $version is already released. Skipping release."
             echo skipped=true >> $GITHUB_OUTPUT
             exit 0