plugin text syntaxes: remove side effect on init: When text syntaxes was initialised, `syntaxes` dict was filled, but it was a class attribute. As a result, re-initialising it (which may happen for tests, and maybe in the future dynamically), was not starting with an empty dict, but with an already-filled one, resulting in conflicts. This patch fixes it by moving `syntaxes` to an instance attribute.

FROM libervia/web: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