plugin pubsub signature: fix attachment setting + default signer: - attachment setting was crashing when `item_elt` was not specified due to argument typo - if `signer` is set to None in attachment data, client's bare jid will be used to sign the item rel 381

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