User agent for WebFinger (#7531)

* User agent for WebFinger

* local_domain → web_domain

* 'http' is away accidentally...

config/initializers/http_client_proxy.rb

@@ -18,7 +18,8 @@ module Goldfinger
   def self.finger(uri, opts = {})
     to_hidden = /\.(onion|i2p)(:\d+)?$/.match(uri)
     raise Mastodon::HostValidationError, 'Instance does not support hidden service connections' if !Rails.configuration.x.access_to_hidden_service && to_hidden
-    opts = opts.merge(Rails.configuration.x.http_client_proxy).merge(ssl: !to_hidden)
+    opts = { ssl: !to_hidden, headers: {} }.merge(Rails.configuration.x.http_client_proxy).merge(opts)
+    opts[:headers]['User-Agent'] ||= Mastodon::Version.user_agent
     Goldfinger::Client.new(uri, opts).finger
   end
 end