Update dockerfile

Author: NorbertLoh

frontend/peerprep/Dockerfile

@@ -1,6 +1,6 @@
 FROM node:20-alpine AS development-dependencies-env
-COPY . /app
 WORKDIR /app
+COPY package*.json ./
 RUN npm ci
 
 FROM node:20-alpine AS production-dependencies-env
@@ -19,4 +19,4 @@ COPY ./package.json package-lock.json /app/
 COPY --from=production-dependencies-env /app/node_modules /app/node_modules
 COPY --from=build-env /app/build /app/build
 WORKDIR /app
-CMD ["npm", "run", "start"]
+CMD ["npm",  "start"]