Bump required version to Elixir 1.12 and remove legacy tests

Drops support for OTP < 22

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

docker/tests/Dockerfile-legacy

@@ -1,33 +0,0 @@
-# We build Elixir manually to have the oldest acceptable version of OTP
-FROM erlang:21
-LABEL maintainer="Thomas Citharel <tcit@tcit.fr>"
-
-# elixir expects utf8.
-ENV ELIXIR_VERSION="v1.11.4" \
-    LANG=C.UTF-8
-
-RUN set -xe \
-    && ELIXIR_DOWNLOAD_URL="https://github.com/elixir-lang/elixir/archive/${ELIXIR_VERSION}.tar.gz" \
-    && ELIXIR_DOWNLOAD_SHA256="85c7118a0db6007507313db5bddf370216d9394ed7911fe80f21e2fbf7f54d29" \
-    && curl -fSL -o elixir-src.tar.gz $ELIXIR_DOWNLOAD_URL \
-    && echo "$ELIXIR_DOWNLOAD_SHA256  elixir-src.tar.gz" | sha256sum -c - \
-    && mkdir -p /usr/local/src/elixir \
-    && tar -xzC /usr/local/src/elixir --strip-components=1 -f elixir-src.tar.gz \
-    && rm elixir-src.tar.gz \
-    && cd /usr/local/src/elixir \
-    && make install clean
-
-CMD ["iex"]
-
-ENV REFRESHED_AT=2021-10-11
-RUN apt-get update -yq && apt-get install -yq build-essential inotify-tools postgresql-client git curl gnupg xvfb libgtk-3-dev libnotify-dev libgconf-2-4 libnss3 libxss1 libasound2 cmake exiftool python3-pip python3-setuptools
-RUN curl -sL https://deb.nodesource.com/setup_12.x | bash && apt-get install nodejs -yq
-RUN npm install -g yarn wait-on
-RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
-RUN mix local.hex --force && mix local.rebar --force
-# Weasyprint 53 requires pango >= 1.44.0, which is not available in Stretch.
-# TODO: Remove the version requirement when elixir:latest is based on Bullseye
-# https://github.com/erlang/docker-erlang-otp/issues/362
-# https://github.com/Kozea/WeasyPrint/issues/1384
-RUN pip3 install -Iv weasyprint==52 pyexcel_ods3
-RUN curl https://dbip.mirror.framasoft.org/files/dbip-city-lite-latest.mmdb --output GeoLite2-City.mmdb -s && mkdir -p /usr/share/GeoIP && mv GeoLite2-City.mmdb /usr/share/GeoIP/