Switch to the Beeper-maintained fork of mx-puppet-discord

Building mx-puppet-discord appears to have been broken for a while.

Related to:
- https://github.com/matrix-discord/mx-puppet-discord/issues/201
- https://github.com/matrix-discord/mx-puppet-discord/issues/202
- https://github.com/matrix-discord/mx-puppet-discord/issues/203

We'd rather use a fork that is maintained better and by someone who
cares about whether their software works or not, so we'll be using the
Beeper-maintained for from now on.

In the future, we should probably do the same for the Slack bridge
which is also part of the same monorepo
(https://gitlab.com/beeper/mx-puppet-monorepo).

roles/matrix-bridge-mx-puppet-discord/tasks/setup_install.yml

@@ -78,6 +78,7 @@
     repo: "{{ matrix_mx_puppet_discord_container_image_self_build_repo }}"
     dest: "{{ matrix_mx_puppet_discord_docker_src_files_path }}"
     force: "yes"
+    version: "{{ matrix_mx_puppet_discord_container_image_self_build_version }}"
   register: matrix_mx_puppet_discord_git_pull_results
   when: "matrix_mx_puppet_discord_enabled|bool and matrix_mx_puppet_discord_container_image_self_build"
 
@@ -88,7 +89,7 @@
     force_source: "{{ matrix_mx_puppet_discord_git_pull_results.changed if ansible_version.major > 2 or ansible_version.minor >= 8 else omit }}"
     force: "{{ omit if ansible_version.major > 2 or ansible_version.minor >= 8 else matrix_mx_puppet_discord_git_pull_results.changed }}"
     build:
-      dockerfile: Dockerfile
+      dockerfile: "{{ matrix_mx_puppet_discord_container_image_self_build_dockerfile_path }}"
       path: "{{ matrix_mx_puppet_discord_docker_src_files_path }}"
       pull: true
   when: "matrix_mx_puppet_discord_enabled|bool and matrix_mx_puppet_discord_container_image_self_build|bool"