Change to ProtocolError in session test

Author: kishkaru

integration/session_test.rb

@@ -809,7 +809,7 @@ def test_can_set_protocol_version_explicitly
 
     # C* 3.0+ does not support protocol version < 3
     if CCM.cassandra_version >= '3.0.0'
-      assert_raises(Cassandra::Errors::NoHostsAvailable) do
+      assert_raises(Cassandra::Errors::ProtocolError) do
         Cassandra.cluster(protocol_version: 2)
       end
     end