fix: align nginx_conf config name with its compose key

Name dropped the _conf suffix, so abra's live-vs-desired lookup
(keyed by compose config name) never matched and always showed
nginx_conf as (new) on deploy, even when unchanged.

compose.yml

@@ -154,7 +154,7 @@ volumes:
 
 configs:
   nginx_conf:
-    name: ${STACK_NAME}_nginx_${NGINX_CONF_VERSION}
+    name: ${STACK_NAME}_nginx_conf_${NGINX_CONF_VERSION}
     file: nginx.conf.tmpl
     template_driver: golang
   fpm_tune: