Fix --tags=register-user not working on Dendrite due to broken Jinja syntax

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/2369

roles/custom/matrix-dendrite/tasks/register_user.yml

@@ -29,6 +29,6 @@
 
 - name: Register user
   ansible.builtin.command:
-    cmd: "{{ {{ matrix_dendrite_bin_path }} }}/create-account {{ username | quote }} {{ password | quote }} {{ '1' if admin == 'yes' else '0' }}"
+    cmd: "{{ matrix_dendrite_bin_path }}/create-account {{ username | quote }} {{ password | quote }} {{ '1' if admin == 'yes' else '0' }}"
   register: matrix_dendrite_register_user_result
   changed_when: matrix_dendrite_register_user_result.rc == 0