Fix test cases

Author: esrakartalOpt

spec/event_builder_spec.rb

@@ -72,7 +72,8 @@
       revision: '42',
       client_name: Optimizely::CLIENT_ENGINE,
       enrich_decisions: true,
-      client_version: Optimizely::VERSION
+      client_version: Optimizely::VERSION,
+      region: 'US'
     }
     @expected_conversion_params = {
       account_id: '12001',