Update Dockerfile

Dockerfile

@@ -2,6 +2,6 @@ FROM python:3.6
 WORKDIR /app
 COPY . .
 # RUN pip install -r requirements.txt  -i https://pypi.douban.com/simple
-RUN pip install -r requirements.txt  -i
+RUN pip install -r requirements.txt
 VOLUME ["/app/proxypool/crawlers/private"]
 CMD ["supervisord", "-c", "supervisord.conf"]