add forgotten support for variable for matrix-bridge-mautrix-facebook role

roles/matrix-bridge-mautrix-facebook/defaults/main.yml

@@ -2,7 +2,7 @@
 # See: https://github.com/tulir/mautrix-facebook
 
 matrix_mautrix_facebook_enabled: true
-matrix_mautrix_facebook_self_build: false
+matrix_mautrix_facebook_self_build: "{{ matrix_container_images_self_build }}"
 
 # See: https://mau.dev/tulir/mautrix-facebook/container_registry
 matrix_mautrix_facebook_docker_image: "dock.mau.dev/tulir/mautrix-facebook:latest"