Update Chinese (Traditional) translation

Co-authored-by: Jeff Huang <s8321414@gmail.com>

locales/zh-TW.json

@@ -470,5 +470,6 @@
     "playlist_button_add_items": "新增影片",
     "channel_tab_podcasts_label": "Podcast",
     "channel_tab_releases_label": "發布",
-    "generic_channels_count_0": "{{count}} 個頻道"
+    "generic_channels_count_0": "{{count}} 個頻道",
+    "toggle_theme": "切換佈景主題"
 }