Add Workhorse maintainers to Danger

This just recognizes files in `workhorse/`. Updates to the the reviewer
roulette or data page will need to be made to populate these fields.

spec/tooling/danger/project_helper_spec.rb

@@ -157,6 +157,9 @@ RSpec.describe Tooling::Danger::ProjectHelper do
       'qa/foo' | [:qa]
       'ee/qa/foo' | [:qa]
 
+      'workhorse/main.go' | [:workhorse]
+      'workhorse/internal/upload/upload.go' | [:workhorse]
+
       'changelogs/foo'    | [:none]
       'ee/changelogs/foo' | [:none]
       'locale/gitlab.pot' | [:none]

tooling/danger/project_helper.rb

@@ -106,6 +106,8 @@ module Tooling
 
         %r{\A(ee/)?qa/} => :qa,
 
+        %r{\Aworkhorse/.*} => :workhorse,
+
         # Files that don't fit into any category are marked with :none
         %r{\A(ee/)?changelogs/} => :none,
         %r{\Alocale/gitlab\.pot\z} => :none,