RUBY-1096 Increase heartbeat_frequency on client used in sdam test

Author: estolfo

spec/mongo/sdam_spec.rb

@@ -11,7 +11,7 @@
 
       before(:all) do
         Mongo::Client.new(spec.uri_string).tap do |client|
-          @client = client.with(connect_timeout: 0.1)
+          @client = client.with(connect_timeout: 0.1, heartbeat_frequency: 100)
         end.close
       end