Add Slovene language (#7475)

app/helpers/settings_helper.rb

@@ -33,6 +33,7 @@ module SettingsHelper
     'pt-BR': 'Português do Brasil',
     ru: 'Русский',
     sk: 'Slovensky',
+    sl: 'Slovenščina',
     sr: 'Српски',
     'sr-Latn': 'Srpski (latinica)',
     sv: 'Svenska',

app/javascript/mastodon/locales/defaultMessages.json

@@ -1857,4 +1857,4 @@
     ],
     "path": "app/javascript/mastodon/features/video/index.json"
   }
-]
+]
\ No newline at end of file

config/application.rb

@@ -67,6 +67,7 @@ module Mastodon
       :'pt-BR',
       :ru,
       :sk,
+      :sl,
       :sr,
       :'sr-Latn',
       :sv,