Set HOSTNAME to 0.0.0.0 for Next.js standalone container

Dockerfile

@@ -61,6 +61,7 @@ USER nextjs
 EXPOSE 3000
 
 ENV PORT=3000
+ENV HOSTNAME="0.0.0.0"
 
 # We need to run migrations before starting the app.
 # Since we are using PostgreSQL and might not have migration files, we use db push