update error predicate

Author: W-A-James

test/integration/auth/mongodb_aws.test.ts

@@ -127,7 +127,8 @@ describe('MONGODB-AWS', function () {
         .catch(e => e);
 
       // Expecting the saslContinue to fail since we changed the conversationId
-      expect(err).to.be.instanceof(MongoError);
+      expect(err).to.be.instanceof(MongoServerError);
+      expect(err.messsage).to.match(/Mismatched conversation id/);
 
       expect(saslStartResult).to.not.be.undefined;
       expect(saslContinue).to.not.be.undefined;