Bump riot web version 1.3.6 -> 1.4.0

roles/matrix-riot-web/defaults/main.yml

@@ -1,6 +1,6 @@
 matrix_riot_web_enabled: true
 
-matrix_riot_web_docker_image: "bubuntux/riot-web:v1.3.6"
+matrix_riot_web_docker_image: "bubuntux/riot-web:v1.4.0"
 matrix_riot_web_docker_image_force_pull: "{{ matrix_riot_web_docker_image.endswith(':latest') }}"
 
 matrix_riot_web_data_path: "{{ matrix_base_data_path }}/riot-web"