Update node:23-alpine Docker digest to 340cd39 (#120)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

backend/Dockerfile

@@ -1,5 +1,5 @@
 # use node 20 alpine image as build image
-FROM node:23-alpine@sha256:5672de224fa400409f65e9b890254c1caf93a3d84665737960626f9419ae4f77
+FROM node:23-alpine@sha256:340cd3926b5116aae1207d6ca1e444d1009aad687c4ad37aa3afbe8a3db591d5
 
 # create work directory in app folder
 WORKDIR /app