uploads: raise upload size limit to 50mb.

config/danbooru_default_config.rb

@@ -92,7 +92,7 @@ module Danbooru
     # Maximum size of an upload. If you change this, you must also change
     # `client_max_body_size` in your nginx.conf.
     def max_file_size
-      35.megabytes
+      50.megabytes
     end
 
     # Maximum resolution (width * height) of an upload. Default: 441 megapixels (21000x21000 pixels).