Remove Keybase integration (#17045)

app/serializers/rest/identity_proof_serializer.rb

@@ -1,17 +0,0 @@
-# frozen_string_literal: true
-
-class REST::IdentityProofSerializer < ActiveModel::Serializer
-  attributes :provider, :provider_username, :updated_at, :proof_url, :profile_url
-
-  def proof_url
-    object.badge.proof_url
-  end
-
-  def profile_url
-    object.badge.profile_url
-  end
-
-  def provider
-    object.provider.capitalize
-  end
-end