fix http-404 for element web with tmpfs

refers to commit
  e65d19884 Run Element Web in tightened/read-only mode without a custom nginx config

and issue
  https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/4199

roles/custom/matrix-client-element/templates/systemd/matrix-client-element.service.j2

@@ -34,7 +34,7 @@ ExecStartPre={{ devture_systemd_docker_base_host_command_docker }} create \
 			--tmpfs=/var/cache/nginx:rw,mode=777 \
 			--tmpfs=/var/run:rw,mode=777 \
 			--tmpfs=/tmp/element-web-config:rw,mode=777 \
-			--tmpfs=/etc/nginx/conf.d:rw,mode=777 \
+			--tmpfs=/etc/nginx/conf.d:rw,mode=777,uid=997 \
 			--mount type=bind,src={{ matrix_client_element_data_path }}/config.json,dst=/app/config.json,ro \
 			--mount type=bind,src={{ matrix_client_element_data_path }}/config.json,dst=/app/config.{{ matrix_server_fqn_element }}.json,ro \
 			{% if matrix_client_element_location_sharing_enabled %}