Pin numpy version

Dockerfile

@@ -19,7 +19,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 RUN pip2 install --upgrade pip && \
     pip2 install --upgrade wheel && \
     pip2 install --upgrade pillow \
-    moviepy \
+    numpy==1.16.4 \
+    moviepy==0.2.3.5 \
     psycopg2-binary \
     pylibmc \
     django-pylibmc