Replace \u2014 with — (#3301)

app/views/layouts/public.html.haml

@@ -7,7 +7,7 @@
     - if !user_signed_in? && single_user_mode?
       %span.single-user-login
         = link_to t('auth.login'), new_user_session_path
-        \u2014
+        —
     %span.domain= link_to site_hostname, root_path
     %span.powered-by
       != t('generic.powered_by', link: link_to('Mastodon', 'https://github.com/tootsuite/mastodon'))