tests: fix test failures when running without API keys.

Fix the test suite failing when trying to run it in the default state
with no config file or API keys configured. Most source sites require
API keys or login credentials to be set in order to work. Skip these
tests when credentials aren't configured.

test/unit/ip_geolocation_test.rb

@@ -1,6 +1,10 @@
 require 'test_helper'
 
 class IpGeolocationTest < ActiveSupport::TestCase
+  setup do
+    skip "IP Registry credentials not configured" unless IpLookup.enabled?
+  end
+
   context "IpGeolocation: " do
     context "the create_or_update! method" do
       should "create a new record if the IP record doesn't already exist" do