refactor: Adjust dockerfile to work without lerna

docker/Dockerfile

@@ -11,10 +11,12 @@ WORKDIR /automatisch
 # copy the app, note .dockerignore
 COPY . /automatisch
 
-RUN yarn
+RUN cd packages/web && yarn
 
 RUN cd packages/web && yarn build
 
+RUN cd packages/backend && yarn --production
+
 RUN \
   rm -rf /usr/local/share/.cache/ && \
   apk del build-dependencies