SP-553 Bump version in Client.php, remove TravisCI

Author: bobbrodie

.travis.yml

@@ -66,7 +66,7 @@
  * Class Client
  * @package Bitpay
  * @author  Antonio Buedo
- * @version 7.3.0
+ * @version 7.4.0
  * See bitpay.com/api for more information.
  * date 15.11.2021
  */