Update Dockerfile

Author: leezhuuuuu

Dockerfile

@@ -13,6 +13,7 @@ RUN apt-get update && apt-get install -y \
     libssl-dev \
     libffi-dev \
     python3-dev \
+    cython \
     && apt-get clean \
     && pip install --no-cache-dir --upgrade pip \
     && pip install --no-cache-dir -r requirements.txt