Update node:23-alpine Docker digest to c61b6b1 (#128)

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:d319827b3b99cca0153f6049fb584a5a4a0ae49252b6dda2314ef564f9857cf2
+FROM node:23-alpine@sha256:c61b6b12a3c96373673cd52d7ecee2314e82bca5d541eecf0bc6aee870c8c6f7
 
 # create work directory in app folder
 WORKDIR /app