tools (datetime, utils): fix incorrect use of naive object: `tools.datetime.format_datetime` was expecting aware datetime objects while `tools.utils.xmpp_date` was returning naive datetime objects. A check has been added to the former one, and latter one has been modified to return aware datetime objects.

ARG REVISION
FROM libervia/web:${REVISION:-dev}

LABEL maintainer="Goffi <tmp_dockerfiles@goffi.org>"

ARG DEBIAN_FRONTEND=noninteractive

USER root

COPY --chown=root:root libervia.conf /etc/libervia.conf

WORKDIR /home/libervia
USER libervia