add support for php 8.0

[uran1980]

Hi, when I run composer install on php 8.0, I get the errors

Problem 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  
    - padrio/php-electrum-api[1.6.1, ..., v1.6.3] require zendframework/zend-hydrator ^2.2 -> satisfiable by zendframework/zend-hydrator[2.2.0, ..., 2.4.2].                                                                                                                                                                                                                                                                                                                                 
    - zendframework/zend-hydrator[2.2.0, ..., 2.2.1] require php ^5.5 || ^7.0 -> your php version (8.0.3) does not satisfy that requirement.                                                                                                                                                                                                                                                                                                                                                 
    - zendframework/zend-hydrator[2.2.2, ..., 2.2.3] require php ^7.0 || ^5.6 -> your php version (8.0.3) does not satisfy that requirement.                                                                                                                                                                                                                                                                                                                                                 
    - zendframework/zend-hydrator[2.3.0, ..., 2.4.2] require php ^5.6 || ^7.0 -> your php version (8.0.3) does not satisfy that requirement.                                                                                                                                                                                                                                                                                                                                                 
    - Root composer.json requires padrio/php-electrum-api ~1.6.1 -> satisfiable by padrio/php-electrum-api[1.6.1, 1.6.2, v1.6.3].

[uran1980]

Instead of old zendframework/zend-hydrator lib try to use https://github.com/laminas/laminas-hydrator

[uran1980]

@see my pull request https://github.com/Padrio/php-electrum-api/pull/25 Thanks