Update nginx Docker tag to v1.31.6

roles/custom/matrix-synapse/defaults/main.yml

@@ -1930,7 +1930,7 @@ matrix_synapse_register_user_script_matrix_authentication_service_path: ""
 matrix_synapse_reverse_proxy_companion_enabled: "{{ matrix_synapse_enabled and matrix_synapse_workers_enabled }}"
 
 # renovate: datasource=docker depName=nginx
-matrix_synapse_reverse_proxy_companion_version: 1.31.5-alpine
+matrix_synapse_reverse_proxy_companion_version: 1.31.6-alpine
 
 matrix_synapse_reverse_proxy_companion_base_path: "{{ matrix_synapse_base_path }}/reverse-proxy-companion"
 matrix_synapse_reverse_proxy_companion_confd_path: "{{ matrix_synapse_reverse_proxy_companion_base_path }}/conf.d"