Switch matrix-registration to v0.7.1

Now that a new release has been made, we no longer need to use
`latest` / `master`.

Related to 0a9109771d and https://github.com/ZerataX/matrix-registration/issues/43

roles/matrix-registration/defaults/main.yml

@@ -12,7 +12,7 @@ matrix_registration_config_path: "{{ matrix_registration_base_path }}/config"
 matrix_registration_data_path: "{{ matrix_registration_base_path }}/data"
 matrix_registration_docker_src_files_path: "{{ matrix_registration_base_path }}/docker-src"
 
-matrix_registration_version: "latest"
+matrix_registration_version: "v0.7.1"
 
 matrix_registration_docker_image: "{{ matrix_registration_docker_image_name_prefix }}devture/zeratax-matrix-registration:{{ matrix_registration_version }}"
 matrix_registration_docker_image_name_prefix: "{{ 'localhost/' if matrix_registration_container_image_self_build else 'docker.io/' }}"