fix: add missing lines

Signed-off-by: Luka Trovic <luka@nextcloud.com>

Author: luka-nextcloud

package-lock.json

@@ -35,6 +35,7 @@
     "@nextcloud/moment": "^1.3.4",
     "@nextcloud/paths": "^2.2.1",
     "@nextcloud/router": "^3.0.1",
+    "@nextcloud/viewer": "^1.0.0",
     "@nextcloud/vue": "^8.26.1",
     "vue": "^2.7.16",
     "vue-material-design-icons": "^5.3.1"