Update translation files

Updated by "Remove blank strings" add-on in Weblate.

Translation: Trilium Notes/Client
Translate-URL: https://hosted.weblate.org/projects/trilium/client/

apps/client/src/translations/ru/translation.json

@@ -635,7 +635,6 @@
         "toggle-zen-mode": "Режим дзен"
     },
     "zpetne_odkazy": {
-        "relation": "",
         "backlink": "{{count}} ссылки",
         "backlinks": "{{count}} ссылок"
     },