Install python

Mark-Simulacrum · Mark-Simulacrum · commit c5b2d8d870b0 · 2018-12-10T06:51:14.000-07:00
It's needed for the configure script to work, and the minimal
installation apparently no longer contains it.
diff --git a/Dockerfile b/Dockerfile
@@ -9,6 +9,7 @@ RUN apt-get update -y && \
       make \
       libssl-dev \
       pkg-config \
+      python \
       python3-venv \
       python3-pip \
       python3-setuptools \
