Move to py3 and pin versions

Dockerfile

@@ -7,15 +7,10 @@ COPY . ${WORKDIR}
 
 COPY sbin/* /sbin/
 
-# TODO(decentral1se): install python3, pip3 instead
+RUN apk --no-cache add ca-certificates mysql-client py3-pip
 
-RUN apk --no-cache add \
+RUN pip3 install --upgrade pip==20.0.2
-  ca-certificates \
-  mysql-client \
-  py-pip
 
-RUN pip install --upgrade pip
+RUN pip3 install --no-cache-dir crudini==0.9
-
-RUN pip install --no-cache-dir crudini
 
 ENTRYPOINT ["/sbin/entrypoint.sh"]