Use pip install with --no-cache-dir in the Dockerfile (#89)

This will help minimize the Docker image size a bit.

Author: PeterDaveHello

Dockerfile

@@ -7,7 +7,7 @@ COPY LICENSE \
         requirements.txt \
         /code/
 
-RUN pip install -r /code/requirements.txt
+RUN pip install --no-cache-dir -r /code/requirements.txt
 
 ENTRYPOINT ["/code/entrypoint.sh"]
 CMD []