Mastodon API: URI encode hashtag name in generated URLs

Otherwise hashtags with word characters other than those allowed in URLs (e.g. Japanese characters) produce hashtag URLs that are invalid.

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -499,7 +499,7 @@ def build_tags(object_tags) when is_list(object_tags) do
     object_tags = for tag when is_binary(tag) <- object_tags, do: tag
 
     Enum.reduce(object_tags, [], fn tag, tags ->
-      tags ++ [%{name: tag, url: "/tag/#{tag}"}]
+      tags ++ [%{name: tag, url: "/tag/#{URI.encode(tag)}"}]
     end)
   end