Update base image in Dockerfile

Changed the base image from 'base' to 'node:20-slim' in the Dockerfile. This change was required as the 'base' image did not include certain necessary dependencies that 'node:20-slim' includes. These dependencies are essential for the effective running of the application.

backend/Dockerfile

@@ -8,7 +8,7 @@ WORKDIR /app
 FROM base AS build
 RUN --mount=type=cache,id=pnpm,target=/pnpm/store pnpm install --prod --frozen-lockfile
 
-FROM base
+FROM node:20-slim
 COPY --from=build /app /app
 
 RUN npm install pm2 -g