Adjust BoardLabel specs

spec/models/board_filter_label_spec.rb → spec/models/board_label_spec.rb

 require 'spec_helper'
 
-describe BoardFilterLabel do
+describe BoardLabel do
   describe 'validations' do
     it { is_expected.to validate_presence_of(:board) }
     it { is_expected.to validate_presence_of(:label) }