Install python

Dockerfile

@@ -9,6 +9,13 @@ ENV LIVEBOOK_APPS_PATH_WARMUP "manual"
 ENV LIVEBOOK_DATA_PATH "/data"
 ENV LIVEBOOK_PORT 7860
 
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    python3.5 \
+    python3-pip \
+    && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
 RUN pip3 install nltk
 
 EXPOSE 7860