fix: backend/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-AOM-7197979
- https://snyk.io/vuln/SNYK-DEBIAN12-EXPAT-7855502
- https://snyk.io/vuln/SNYK-DEBIAN12-EXPAT-7855502
- https://snyk.io/vuln/SNYK-DEBIAN12-EXPAT-7855503
- https://snyk.io/vuln/SNYK-DEBIAN12-GIT-6846203

backend/Dockerfile

@@ -1,5 +1,5 @@
 # Usar una imagen base de Node.js
-FROM node:22.6.0
+FROM node:22.8
 
 # Establecer el directorio de trabajo
 WORKDIR /usr/src/app