upd: add python

Dockerfile

@@ -10,6 +10,11 @@ WORKDIR /sharkey
 
 RUN apk add git
 
+ENV PYTHONUNBUFFERED=1
+RUN apk add --update python3 && ln -sf python3 /usr/bin/python
+RUN python3 -m ensurepip
+RUN pip3 install --no-cache --upgrade pip setuptools
+
 COPY . ./
 
 RUN git submodule update --init --recursive