add sqlite3 in image.

docker/Dockerfile.dev

@@ -5,6 +5,15 @@ FROM python:3.6.6-slim-stretch
 # Ensure use of bash
 SHELL ["/bin/bash","-c"]
 
+# Sqlite3
+RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
+ARG DEBIAN_FRONTEND=noninteractive
+RUN apt-get update \
+&& apt-get install -yq apt-utils \
+&& apt-get install -yq sqlite3 \
+&& apt-get install -yq curl \
+&& rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+
 # Install flask
 COPY requirements.txt requirements.txt
 RUN pip install --trusted-host pypi.python.org -r requirements.txt